Despite being ranked so highly, Peta Gillyatt, a spokesperson for HMS, said potential applicants ought to take such rankings with a grain of salt.

"We're very pleased to be number 1, but the U.S. News rankings are a quantitative survey and it is not possible to capture the many facets of the medical school experience in it," Gillyatt said.

According to an explanatory article on the magazine's educational ranking web site, www.usnews.com/usnews/edu/, the rankings are based on test scores, faculty-to-student ratio, "insider ratings," budget and research grants, starting salaries for graduates, among other criteria.

Schools can receive a weighted average of 100 points. HMS placed first with its 100.0 score, which was 27 points ahead of its nearest competitor, Johns Hopkins in Baltimore

Most of the graduate programs run by Harvard's Graduate School of Arts and Sciences (GSAS) were clustered individually in the survey.

Though the GSAS ranked within the top seven for nearly every one of its programs, Harvard's Ph.D program in computer science placed 17th, tied with Purdue.