Marianna Stango Rodino, 70, wife of Rep. Peter J. Rodino Jr. (D-N.J.) died of cancer Wednesday at the Monmouth Medical Center in Long Branch, N.J.

Known to her family and friends as Ann, Mrs. Rodino lived in Newark, N.J., all her life. She met the future Congressman, who is now chairman of the House Judiciary Committee, at a mass at a Newark church in 1926. They were married in 1941.

Rodino has called his wife his "best campaigner . . . a great source of strength and comfort to me through the most difficult times of my life."

Mrs. Rodino was active in many community and charitable organizations and was the former chairwoman of the Essex County March of Dimes.

Last summer, a home for the aged was named in her honor in Majano, Italy, in the northern province of Udine. The United States helped build the center after an earthquake destroyed the town in 1976. The congressman attended the dedication ceremonies, but Mrs. Rodino was unable to be there because of her health.

The Rodinos have two children, Margaret Stanziale of West Orange, N.J., and Peter III, of Monmouth Beach, N.J., and two grandchildren. Mrs. Rodino's mother and four brothers also survive.

The family suggests that expressions of sympathy be in the form of contributions to the Marianna Stango Rodino Home for the Aged Fund, c/o Rodino, Foreman & D'Uva, 141 S. Harrison St., East Orange, N.J., 07018.