James N. Schuth, a tax lawyer who was a partner in the law firm of Gebhardt and Smith, died Monday after a heart attack while exercising at the Downtown Athletic Club. He was 46 and lived on East Montgomery Street.

Services for Mr. Schuth will be held at 11:30 a.m. tomorrow at Old St. Paul's Episcopal Church, Charles and Saratoga streets.

He had been associated with the firm of Miles and Stockbridge since 1975, becoming a partner in 1980. He joined Gebhardt and Smith in 1988.

Born in Oak Park, Ill., he was a 1968 graduate of Drake University and a 1971 graduate of the University of Illinois Law School.

He was a member of the American Bar Association and the City Bar Association as well as the Maryland State Bar Association and its ethics committee.

He is survived by his wife, the former Mary Kee Hood; a son, Samuel Otto Schuth of Baltimore; a daughter, Ashley Noelle Schuth of Washington; his mother, Hazel Proctor Schuth of River Forest, Ill.; and two sisters, Maureen Darling of West Chicago, Ill., and Miriam R. Reyher of Pine Lake, N.J.