The segregation of black students is intensifying in public schools in the Northeast and the Midwest, and the isolation of Hispanic pupils is growing dramatically across the country, according to a major new study of desegregation trends.

While the study, noted general desegregation progress between 1968 and 1980, with millions of children moving into biracial classrooms, it reported huge disparities between regions and increasing segregation of blacks, particularly in the Northeast, and Hispanics outside the South.

In 1980, for example, 63 percent of black students and 68 percent of Hispanics were in segregated schools, that is, schools with more than half minority enrollment. In contrast, 12 years earlier, 77 percent of blacks and 55 percent of Hispanics were in such schools.

In the South, however, where federal civil rights enforcement has been concentrated, the desegregation trend went the other way. In 1968, 81 percent of black students in that 11-state region were in predominantly minority schools. By 1980; the figure was 57 percent, the best regional mark in the country.

Illinois, with large concentrations of blacks in Chicago and East St. Louis, was the nation's most segregated state for black students in 1980, almost double its nearest challenger in the South. Sixty-eight percent of Illinois' black students were in schools that were 90 to 100 percent minority. Louisiana and Mississippi, the most segregated southern states, each had 37 percent of blacks in intensely segregated schools.

The study was done by University of Chicago professor Gary Orfield for the Washington-based Joint Center for Political Studies at the request of a House Judiciary subcommittee.

The subcommittee on civil and constitutional rights, chaired by Rep. Don Edwards (D-Calif.), is holding extensive hearings on school desegregation and has scheduled a meeting for Thursday to hear Orfield and others discuss the study. Orfield used 1968-1980 population data from the U.S. Department of Education as the basis of his analysis.

Orfield said "the most remarkable changes have occurred in the South," which he attributed largely to federal pressure to break down racial barriers for blacks. But, he added, "There has been no progress on integrating Latino students in public schools in the 1970s. In fact, each region of the country has become more segregated for Hispanics as their numbers have rapidly grown in American society."

He said the findings on the growing segregation of Hispanics raised "very important research and policy questions." The large increase of Hispanic segregation and gradual decline of black segregation during the last decade meant that a typical Latino student in 1980 attended a more segregated school that the typical black.

"The consistent trend toward greater segregation and the acceleration of that trend in the late 1970s suggested that the gap could widen," Orfield said. "The fact that we have another large rapidly growing minority that is already by some measures more segregated than blacks... suggests the need for the most serious examination of an urban society where there would be essentially separate systems of schooling not only for blacks and whites but also for Latinos.

"The West is by far the most important region for Hispanics [44 percent of the nation's Hispanic students are there] and what happens to Hispanic students will have a far larger impact on the West than any other region."

Orfield, a longtime student of public school racial trends, found that the most significant changes occurred in the 11 southern and six border states that were segregated by law before 1954. Most of the major desegregation was achieved by 1972, he wrote. During the 1970s all regions except the Northeast reduced black segregation to some degree.

"The Northeast, by far the nation's most segregated region, became more segregated during the decade," Orfield said. "The 1980-81 school year found almost half of the black students in the Northeast in 90-100 percent minority schools, but fewer than half this percentage in the South."

Orfield said that "the most remarkable changes," which he found in the South and a few other states elsewhere, seemed "to be clearly related to policies and enforcement efforts by the courts and federal executive agencies. Pressure has diminished in recent years and so has progress. There has been no serious effort to provide integration for Hispanics and their segregation is rapidly increasing."