Training to become a doctor takes so long that just the time invested has become, to many, emblematic of the gravity and prestige of the profession.

But now one of the nation’s premier medical schools, New York University, and a few others around the United States are challenging that equation by offering a small percentage of students the chance to finish early, in three years instead of the traditional four.

Administrators at NYU say they can make the change without compromising quality, by eliminating redundancies in their curriculum, getting students into clinical training more quickly and adding extra class time in the summer.

Not only, they say, will those doctors be able to hang out their shingles to practice earlier, but they will save a quarter of the cost of medical school — $49,560 a year in tuition and fees at NYU, and even more when room, board, books, supplies and other expenses are added in.

“We’re confident that our three-year students are going to get the same depth and core knowledge, that we’re not going to turn it into a trade school,” said Dr. Steven Abramson, vice dean for education, faculty and academic affairs at NYU School of Medicine.

At this point, the effort involves a small number of students at three medical schools: about 16 incoming students at NYU, or about 10 percent of next year’s entering class; nine at Texas Tech Health Science Center School of Medicine; and even fewer, for now, at Mercer University School of Medicine’s campus in Savannah, Ga. A similar trial at Louisiana State University has been delayed because of budget constraints.

But Dr. Steven Berk, the dean at Texas Tech, said that 10 or 15 other schools across the country had expressed interest in what his university was doing, and the deans of all three schools say that if the approach works, they will extend the option to larger numbers of students.

“You’re going to see this kind of three-year pathway become very prominent across the country,” Abramson predicted.

The deans say that getting students out the door more quickly will accomplish several goals. By speeding up production of physicians, they say, it could eventually dampen a looming doctor shortage, although the number of doctors would not increase unless more students are admitted to future classes.

The three-year program would also curtail student debt, which now averages $150,000 by graduation, and by doing so, persuade more students to go into shortage areas like pediatrics and internal medicine, rather than more lucrative specialties like dermatology.

The idea was supported by Dr. Ezekiel Emanuel, a former health adviser to President Barack Obama, and a colleague, Victor Fuchs. In an editorial in the Journal of the American Medical Association in March, they said there was “substantial waste” in the nation’s medical education. “Years of training have been added without evidence that they enhance clinical skills or the quality of care,” they wrote. They suggested that the 14 years of college, medical school, residency and fellowship that it now takes to train a subspecialty physician could be reduced by 30 percent, to 10 years.

That opinion, however, is not universally held. Other experts say that a three-year medical program would deprive students of the time they need to delve deeply into their subjects, to consolidate their learning and to reach the level of maturity they need to begin practicing, while adding even more pressure to a stressful academic environment.

“The downside is that you are really tired,” said Dr. Dan Hunt, co-secretary of the Liaison Committee on Medical Education, the accrediting agency for medical schools in the United States and Canada. But because accreditation standards do not dictate the fine points of curriculum, the committee has approved NYU’s proposal, which exceeds by five weeks its requirement that schools provide at least 130 weeks of medical education.

The medical school is going ahead with its three-year program despite the damage from Hurricane Sandy, which forced NYU Langone Medical Center to evacuate more than 300 patients at the height of the storm and temporarily shut down three of its four main teaching hospitals.

Abramson of NYU said that postgraduate training, which typically includes three years in a hospital residency, and often fellowships after that, made it unnecessary to try to cram everything into the medical school years. Students in the three-year program will have to take eight weeks of class before entering medical school, and stay in the top half of their class academically. Those who do not meet the standards will revert to the four-year program.

The three-year programs at Texas Tech and Mercer are focused on producing doctors who want to go into family medicine, which administrators insist is not because family medicine is easier, but because they are responding to the need for more primary and preventive care.

That focus on only one category of doctors has disturbed some proponents of three-year schools. Dr. Bruce Wright, associate dean of undergraduate medical education at Calgary, said it could create a perception that three-year programs were “medical school lite,” turning out second-class physicians. The trend, he suggested, could ultimately lead to lower standards for family medicine graduates, who are already in a lower-paid, lower-prestige field.

NYU has decided to open its three-year program to students regardless of what branch of medicine they plan to go into, but Abramson said it would look for students interested in primary care fields like internal medicine, pediatrics and obstetrics. Students will have to declare their choice when they apply, because they will be guaranteed residencies in an NYU-affiliated hospital, as a way of lessening anxiety that other residency programs might be wary of their three-year degrees.

The adjustment would be easier for NYU, he said, because it has already changed its curriculum to begin clinical studies in the first two years, rather than in the traditional third and fourth years, and it already accommodates some students who are earning both medical degrees and master’s degrees in public health within four years.

Emanuel said he would like to see an even bolder approach, like offering the three-year program to 20 percent of the class. “But it’s progress,” he said. “It’s a major school and a place of high visibility.”