Fulton Lee Farrish, 50, president of the Farrish Oldsmobile, Jeep and Subaru automobile firm at Fairfax Circle, died Saturday at Fairfax Hospital. He had hepatitis.

Mr. Farrish opened the Fairfax Auto Body Co. in 1958. Two years later, he formed the City Auto Glass Co. He continued to expand, adding the Kaiser Jeep Dealership in 1967, the Oldsmobile franchise in 1973 and the Subaru franchise in 1977.

He was an organizer and the first president of the Washington Metropolitan Auto Body Association. He had been editor of its trade magazine, "The Hammer and Dolly." He had served as vice president of the National Auto Body Association.

Mr. Farrish was born in Charlottesville, Va. He came to this area in 1946 and worked as an auto body repair apprentice and service manager for several private firms before opening his own business. He lived in Clifton, Va.

He had served on the advisory boards of the Family Savings and Loan Association and the Guaranty Bank and Trust Co. in Northern Virginia and was a member of the Fairfax City and Fairfax County Chambers of Commerce and the Better Business Bureau of Metropolitan Washington.

Mr. Farrish helped organize the Fairfax Police Boys Club, was an honorary member of the Fairfax Lions Club, a past officer of the Kiwanis Club and belonged to the Elks and Moose Lodges, the Masons, Scottish Rite and the Shrine and the Fairfax Wildlife Club.

He is survived by his wife, Marilyn H., and three children, Kathy, Keith and Kevin, all of Clifton; three brothers, Harold (Mike) of Culpeper, Va., Marion, of Springfield, Va., and William (Johnny), of Burke, Va., and two sisters, Mary Melvin, of Clifton, and June Jones, of Fredericksburg.

The family suggests that expressions of sympathy be in the form of contributions to the American Digestive Disease Society, 7720 Wisconsin Ave., Suite 217, Bethesda, Md. 20014.