Alfred B. Lawson Jr., 58, the development director of the Children's Hospital National Medical Center since 1966, died of a heart ailment Oct. 25 at his home in Washington.

Hospital officials credited Mr. Lawson with raising more than $30 million for the institution during his career there. He was responsible for raising funds for the hospital's new building, which was opened in 1977, and was a founder of the Ronald MacDonald House, a Children's Hospital residential facility for the parents of children with long-term illnesses.

Mr. Lawson was born in Danbury, Conn., and served in the Army in Europe in World War II. He attended George Washington University. He was an assistant sales manager at the Mayflower Hotel, director of the Humane Society in Delaware, a fund-raiser for the American Red Cross and the public relations director of the American Cancer Society in Nassau County, N.Y.

In 1962, he returned here as director of fund-raising for the Washington Heart Association. He was named director of development at Children's Hospital four years later.

Mr. Lawson was a member of the National Society of Fund Raisers and the National Association for Hospital Development. The Greater Washington chapter of the National Society of Fundraising Executives gave him its Professional Fund Raiser of the Year Award for 1982.

Mr. Lawson also was a member of the Washington Board of Trade, the Georgetown Kiwanis Club and the vestry of St. John's Episcopal Church.

Survivors include two sisters, Betty Shepard of Hobe Sound, Fla., and Barbara Orlando of Danbury.