For ambitious young scientists trying to start their own research labs, winning a prestigious grant from the National Institutes of Health can be career making.

But when it comes to the size of those awards, men are often rewarded with bigger grants than women, according to a study published Tuesday in JAMA, which found that men who were the principal investigators on research projects received $41,000 more than women.

The disparity was even greater at the nation’s top universities. At Yale, women received $68,800 less than men, and at Brown, the median disparity was $76,500. Over all, the median N.I.H. award for female researchers was roughly $126,600, compared with $167,700 for men.

The study, by researchers at Northwestern University, confirms longstanding disparities between men and women in the field of science. In recent years, a cavalcade of studies has documented biases that favor male researchers in hiring, pay, prize money, speaking invitations and even the effusiveness displayed in letters of recommendation.