The Wolf Trap Foundation has filed a lawsuit against the New National Theatre Corporation (NNTC) for breach of contract, according to papers filed with the D. C. Superior Court last month. In the suit, the foundation seeks $85,000, the sum Wolf Trap claims is its outstanding share of box-office revenues, plus reimbursement for unauthorized expenses, resulting from the four-week run of the musical "Brigadoon" at the National Theatre in the fall of 1980.

The New National Theatre Corp., the nonprofit organization that runs the National Theatre, has denied that it owes Wolf Trap any money. "We really regret the action of Wolf Trap," said NNTC's general counsel, Joseph Fontana, yesterday. "We have paid all our just claims. We do not believe there is any merit to their complaint."

In an agreement between the two organizations, Wolf Trap produced "Brigadoon" and presented it for a week at Wolf Trap Farm Park. The production then moved for a month to the National Theatre , where it did mediocre business. The agreement included a schedule for the distribution of "Brigadoon's" National grosses between the two organizations. "Brigadoon" subsequently enjoyed a modest run on Broadway during the 1980-81 season.

Attorneys for both parties have attempted to resolve the matter over the past 18 months. Fontana said "we would prefer to settle this out of court." But a spokesman for Arent, Fox, Kintner, Plotkin & Kahn, which represents the Wolf Trap Foundation, refused to comment on that possibility yesterday.