A research grant application from a black scientist to the National Institutes of Health is markedly less likely to win approval than one from a white scientist, a new study reported on Thursday.

Even when the researchers made statistical adjustments to ensure they were comparing apples to apples — that is, scientists at similar institutions with similar academic track records — the disparity persisted. A black scientist was one-third less likely than a white counterpart to get a research project financed, the study found.

“It is striking and very disconcerting,” said Donna K. Ginther, a professor of economics at the University of Kansas who led the study. “It was very unexpected to find this big of a gap that couldn’t be explained.”

The findings are being published in Friday’s issue of the journal Science.

At the N.I.H., which commissioned the study, top officials said they would follow up to figure out the causes of the disparity and take steps to fix it.