Nearly three-quarters of the students assigned to kindergarten at Rosemary Hills Elementary School in Silver Spring as part of an integration plan have enrolled, a number far greater than predicted after some parents said last year they would send their children to private schools instead.

School officials told the Montgomery County Board of Education last night that 104 of the 140 kindergarten-age students assigned to the school in the predominantly minority area showed up during the first week of school. The enrollment, school officials said, was split evenly between minority and white students.

Assistant area superintendent Patricia Sweeney told the board that it "was too early to draw any conclusions" about what effect the figures would have on long-term integration in the area, but she said the figures had been a great surprise.

School officials had expected kindergarten-age enrollment to be as low as 70 students this year after 31 of 42 parents of Chevy Chase students assigned to Rosemary Hills signed sworn statements that they intended to send their children to private schools rather than participate in the busing plan reinstated this month.

School officials could not say last night how many of those Chevy Chase parents had actually gone forward with their plans not to enroll their children in public schools, but they said that it seemed obvious that not all had.

Board President Blair Ewing, who spearheaded the effort last fall to revive the busing plan, said he was pleased with the results.

Under the plan, kindergartners are bused from the predominantly white Chevy Chase and North Chevy Chase elementary school areas to Rosemary Hills. (In future years, first and second graders also will be bused to Rosemary Hills.) Children from Rosemary Hills are bused to Chevy Chase or North Chevy Chase elementaries for grades three through six. "I'm glad events have proven the predictions wrong," Ewing said.

Rosemary Hills was the focus of debate over the county's efforts toward racial integration and the centerpiece of the county's voluntary busing efforts when the school board, led by board member Marian Greenblatt, voted in 1981 to undo the pairing between Rosemary Hills and Chevy Chase schools.

That action was reversed last March by the newly elected school board, but not without considerable protest--including the threats to withdraw from the public school system by some parents in Chevy Chase.

In addition to the Rosemary Hills figures, Sweeney said last night that 19 more students than expected showed up at Chevy Chase Elementary, with 67 percent of its student body white and 33 percent minority students. She also said that three fewer students than expected enrolled at North Chevy Chase Elementary, with 51 percent white and 49 percent minority students.