Richard Gustav Heintze, 42, a concert, jazz and pop music pianist who had performed since the age of 9, died Tuesday at the Washington Adventist Hospital of amyotrophic lateral sclerosis, also known as Lou Gehrig's disease. He lived in Suitland.

Born in Washington, he was a graduate of Woodrow Wilson High School. He began studying piano at the age of 4 and five years later he performed on radio. He studied at the Eastman School of Music in Rochester, N.Y., and at American University here, as well as with a number of well-known concert pianists.

Mr. Heintze had played in concert with the Washington Civic Orchestra and the National Symphony Orchestra. He had performed at Carnegie Hall and Kennedy Center and at concert halls throughout the country. In 1973, he gave concerts in Switzerland, Germany and England. He also had participated in Newport Jazz Festivals.

In 1963-65, while serving with the U.S. Army at Fort Hood, Tex., he directed the Army chorus, which he took on tour of the country.

Mr. Heintze had been with numerous bands in the Washington area. In 1978 he gave his last performance, 10 area bands gave a benefit performance to honor him.

Survivors include his wife, Marcia, from whom he was estranged, and three daughters, Valerie Lynn, Laurie Joan and Karen Ruth, all of Bethesda; his parents, Gustave Joseph and Ruth Wilson Heintze of Washington; two brothers, Gustav Joseph Jr., of Silver Spring, and James Rudolph, of Kensington; and a sister, Anna May Haymes of Roanoke.