Walter W. Barto Jr., 41, a vice president of the SmithKline Corp. pharmaceutical firm and a member of the business-public affairs advisory group to the White House Office of Public Affairs, died of cancer Saturday at Abington Memorial Hospital in Abington, Pa.

Mr. Barto had worked for SmithKline since 1963. In 1972, he was appointed a Presidential Interchange Executive and served for a year as deputy director of the office of public affairs of the Environmental Protection Agency in Washington. In 1973, he was named to the President's Commission on Personnel Interchange, which advises the White House on the exchange of executives between business and the government He was reapointed in 1976.

He was named to the advisory group to the White House Office of Public Affairs in 1977.

Since February 1978, Mr. Barto had been vice president of U.S. pharmaceutical marketing for SmithKline, which is headquartered in Philadelphia. He lived in Meadowbrook, Pa.

He was a member of the Public Relations Society of America, the International Management and Development Institute and the National Press Club and the University Club in Washington.

Survivors include his wife, Diana, and four daughters, Stacy, Stephanie, Susan and Jennifer, all of the home in Meadowbrook; his mother, Mary Barto, of Salunga, Pa.; his father, Walter W. Barto Sr., of Honey Brook, Pa., and a sister, Mary Elaine Hughes, also of Salunga.

The family suggests that expressions of sympathy be in the form of contributions to the Abington Presbyterian Church, Abington, Pa.