The PTA of Grosvenor Elementary School in Bethesda and eight parents who send their children to that school have filed a $1 million suit against the Montgomery County school board, seeking to prevent it from closing the school in June.

The suit, filed Friday in Circuit Court in Rockville, charges that the board's decision to close the school was made arbitrarily and without following established school board procedures.

The PTA and parents have asked the court to keep the school open until the proper procedures are followed.

Last month, the seven-member Montgomery school board voted to close Grosvenor and five other schools as part of a comprehensive five-year plan to adjust the school system to declining enrollment.

Since 1972, the system's peak enrollment year, the student population in Montgomery schools has dropped by 24,000 from just over 126,000 and as a result, the board has closed 24 schools.

Carl Schulz, head of the Grosvenor PTA, said yesterday he believed the board had unfairly voted to close Grosvenor because it relied solely on enrollment projections without examining other criteria, such as racial balance, need for renovation and distribution percentages to higher schools.

"We've been deprived of our rights under the Constitution, which provides equal protection and due process," he said. "We think it was a completely arbitrary proceeding and we can only speculate on the reasons."

The PTA also recently appealed the decision to close Grosvenor to the Maryland Board of Education. No hearing date has yet been set, Schulz said.

Kenneth Muir, spokesman for Montgomery schools, said yesterday, "Anytime you threaten anyone's school with closing, they're not happy. All communities fight to keep their schools open, some just continue to fight a lot longer."

Muir said the decision to close Grosvenor was based on the school's rapidly declining enrollment, underutilization of its classrooms and the ability of nearby schools to absorb additional students.

According to school board statistics, Grosvenor has a capacity of 350 students but has an enrollment this year of only 198. Next year, the board predicted a drop of nearly 40 children in the school's population.

However, the PTA contended that the area -- and the school-age population -- will grow rapidly within the next 10 years, due in part to the Grosvenor Metro station that is scheduled to open in 1983.