Winifred Sears Freiot Conradis, 68, a native Washingtonian who was active in hereditary and civic groups and instrumental in blocking efforts to rename a section of historic Rockville Pike, died of cancer Tuesday at a hospital in Sarasota, Fla.

In 1960, when the Maryland-National Capital Park and Planning Commission changed the name of the section of Rockville Pike between Bethesda and Rockville to Wisconsin Avenue, Mrs. Conradis enlisted the help of the Locust Hill Citizens Association in persuading the commission to restore the old name, which was established in 1791.

Mrs. Conradis, a longtime resident of Bethesda, was a member of the Montgomery County Republican Party, the Montgomery County Historical Society and Kenwood Country Club. She was a former president of Alpha Chi Omega Alumnae, a member of the National Society of Magna Carta Dames and the National Society of Daughters of Founders and Patriots of America and a former regent of the Botany Cross Chapter of the Daughters of the American Revolution.

She attended the College of William & Mary in Williamsburg, Va., before earning a bachelor's degree from George Washington University here in 1935. She also earned a degree from the Prince School, a merchandising college, in Boston.

During World War II, Mrs. Conradis helped register aliens under the Wartime Powers Act and worked for the U.S. Public Health Service.

She and her husband of 41 years, Albert E. Conradis, a retired attorney, moved to Longboat Key, Fla., in 1972. He died last year.

Survivors include a daughter, Jocelyn Tully of Cocoa, Fla.; two sons, Gilbert E. of Longboat Key and John C. F. of Washington, and two grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to the American Cancer Society.