Roger J. Gaetjen, 42, an Internal Revenue Service training official and a volunteer coach for the Fort Hunt Youth Club in Alexandria, died of a coronary occlusion Sunday at Mount Vernon Hospital in Alexandria.

Mr. Gaetjen, who was born in San Francisco, was a graduate of the University of California at Berkeley and did postgraduate work at San Francisco State College. He began his IRS career in 1961 as a revenue officer in California.

In 1968, he transferred to the IRS training and stabilization divisions in the Washington area. At the time of his death, he was in charge of the research and audio-visual branch at the IRS National Training Center in Arlington. He received a number of IRS awards for his work.

A resident of the Fort Hunt area of Alexandria and the father of four sons, he coached football, basketball and baseball for the Fort Hunt Youth Club and other organizations. He also coached softball teams.

Survivors include his wife, Debra, and four sons, Mark, Jeff, Scott and Billy, all of Fort Hunt; his parents, Mr. and Mrs. Elmer Gaetgen of San Francisco; a brother, James, of Santa Rosa, Calif., and a sister, Victoria Williams of San Anselmo, Calif.