J. Clayton Cook, a retired director of advertising and mail promotion for the Bureau of National Affairs here, died at his Washington home of a myocardial infarction.

In 1967, Mr. Cook became director of advertising, mail promotion and public relations for the BNA, an employe-owned company that publishes legal, economic, labor, tax, financial, environmental, safety and energy information for business and professional subscribers.

Since his retirement in 1978, he was a BNA consultant and assistant trustee of the company's employe stock purchase and transfer plan.

Mr. Cook began his career in communications in the mid-1930s as a reporter for the Philadelphia Inquirer and was night city editor there from 1941 to 1946. He then worked for a Philadelphia public relations firm until joining the BNA in 1976.

He was born in Haddon Heights, N.J., and graduated from Lafayette College in Easton, Pa.

Mr. Cook was a member of the National Press Club, the Ad Club of Washington and the Direct Mail Marketers Association.

Survivors include his wife, the former Louise Oldt, of Washington; two sons, Charles A., of Haddonfield, N.J., and John M., of Philadelphia; a daughter, Susanne of Burke, Va.; a sister, Francis Underkuffler of Cape May, N.J., and three grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to the American Heart Association.