Johan G. Middelthon, 56, a painter and musician who was a graphic artist for Sauls Lithograph Co. here since 1966, died Thursday at his home in Shadyside, Md. He had a heart ailment.

Mr. Middelthon worked for the Structural Clay Products company, now the Brick Institute of America in McLean, for 20 years before joining Sauls Litograph. His work has appeared in numerous publications, including Architectural Forum magazine. He was the graphic artist for Appalachia Region magazine.

His prize-winning paintings, mostly abstracts and landscapes in oils and acrylics, have been presented in exhibits around the country, including one-man shows in New York City and Chicago, where he won a Chicago Art Fair prize.

Mr. Middelthon played drums with Charlie Byrd's band in the late 1940s and recently was drummer for the Shadyside Blues Band. He was a member of Musicians Local No. 161.

He was born in Gainesville, Va., and attended Washington Lee High School in Arlington and the Abbott Art School.

Survivors include his wife, Patricia Ann, of Shadyside; four sons, Peter J., of Glen Burnie, Christopher, of Arlington, Robert, of Reston, and Johan G. Jr., of Georgetown, Del.; a daughter, Latricia Lee Andre of Arlington, and seven grandchildren.