Rosecroft Raceway opens the area's 120-night harness racing season Thursday, and the Oxon Hill track is gearing up for record mutuel handles if the current stike of racetrack employees continues against Pimlico.

Rosecroft will man all 197 of its mutuel windows - there are 143 sellers and 54 cashiers - for the first three nights and John T. Mathews, the mutuels manager, predicts a $1 million handle one of those nights if the strike is not settled.

The previous high handled at Rosecroft was $677,678 on June 5, 1976.

Rosecroft employees are members of the same union that is striking the three major thoroughbred tracks. But they are covered by a different contract. Only 14 per cent of the Rosecroft employees also work at the thoroughbred tracks.

Meanwhile, Rosecroft has undergone a facelift for the third straight year, part of a $5.6 million improvement program. The emphasis the season was on a remodeled racing oval that is reportedly safer and faster and a new lighting system with five times as much candlepower.

Nine races are scheduled Monday through Thursday, with 10 races Friday and Saturday. Post time is 8 p.m. nightly, with dark days on June 8, 15 and 22. The meet ends June 25.

The highlight of the meeting, as usual, is the $40,000 William E. Miller Memorial Pace. Five of the nation's top nine 3-year-olds are still eligible for the May 20 event, which likely will be raced in two $25,000 divisions.