Recent efforts to get more black and Hispanic students into New York City’s elite public high schools have fallen short, with proportionately fewer of them taking the admissions exam and even lower percentages passing it. The performance gap persists even among students involved in the city’s intensive 16-month test prep institute, designed to diversify the so-called specialized high schools, including the storied triumvirate of Stuyvesant, Bronx Science and Brooklyn Tech.

Among the 21,490 public school students who last year took the exam, the single gateway to eight high schools, 6 percent of blacks and 7 percent of Hispanics were offered admission, compared with 35 percent of Asians and 31 percent of white students. The disparities were the worst at Stuyvesant, where 2 percent of blacks, 3 percent of Hispanics, 24 percent of whites and 72 percent of Asians were accepted. (Over all, 1 in 5 test-takers is offered a spot; racial data is not available on private school students.)

Parents of black and Hispanic students have long complained about the lack of diversity in the elite schools’ enrollment, and the Department of Education promised two years ago to study whether the demographic lopsidedness was the result of certain groups’ doing poorly on the grueling two-and-a-half-hour test, not taking the exam in high numbers, or simply choosing not to attend the schools. The city abandoned that effort, but an analysis by The New York Times shows that not only do blacks and Hispanics lag behind whites and Asians in succeeding on the exam, they are far less likely to take it.

Perhaps most surprising is a close look at the students enrolled in the city’s Specialized High Schools Institute, created 14 years ago to prepare students for high school and recently expanded by Schools Chancellor Joel I. Klein. Black and Hispanic students who attend the institute are more likely to succeed on the test. While 90 percent of Asians and 85 percent of white students at the institute take the test, 65 percent of blacks and 70 percent of Hispanics do; last year, of the institute graduates taking the test, 58 percent of the Asians, 49 percent of whites, 21 percent of Hispanics and 19 percent of blacks were offered admission.