NEW YORK — Robert G. Derx, 78, a retired executive of Vanity Fair, died at St. Mary’s Hospital in Rochester, Minn., on Jan. 21 of a heart attack. Funeral services were held in Minneapolis.

Derx had been vice president in charge of marketing for Vanity Fair, where he was instrumental in establishing that company’s global market.

He is survived by his wife, Marguerite, and a sister, Mildred Hossler of Polson, Mont. A memorial service in Derx’s hometown, New Fairfield, Conn., will be scheduled this spring, said his wife.