Marvin Eliott Preis, 41, senior partner in the law firm of Preis, Cooper and Adams, died of cancer Sept. 5 at George Washington University Hospital.

He had opened his own law offices in Washington in 1963, shortly after graduating from George Washington University Law School. The practice was enlarged and the offices are now located in Silver Spring.

Born in Atlantic City, Mr. Preis was a graduate of the Valley Forge Military Academy and the Wharton School of Finance of the University of Pennsylvania.

He was a member of the D.C. Bar Association and as chairman of the radio committee of its young lawyers section was moderator of radia programs in which it was involved for several years. The association names him Outstanding Young Lawyer of the Year in 1974.

Admitted to practice before the U.S. Supreme Court, Mr. Preis also was a member of the American and Montgomery County Bar Associations, the American Judicature Society and the American Arbitration Association.

He was a past master of Cornerstone Lodge No. 224 of the Masons and belonged to the Fudda Nabi Grotto.

Mr. Preis also was a member of Argo and Potomac Lodges of B'nai B'rith and formerly served on the board of trustees of Temple Emanuel. He belonged to the Men's Club of the National Children's Centre.

An accomplished jazz pianist, he had played at various clubs in the Wasington area, most recently with the Washington Channel Jazz Band.

he is survived by his wife, Barbara Preis, and three sons, Michael, Alan and William, of the home in Potomac; his parents, Mr. and Mrs. Samuel Preis, of Miami, Fla.; a brother, Jerry, of Columbus, Ga., and a sister, Diane Levine, of Brooklyn, N.Y.

The Family suggests that expressions of sympathy be in the form of contributions to theAmerican Cancer Society.