Kenny Doerrer, a 19-year-old sophomore at Winthrop College, shot a 2-under-par 70 yesterday at Woodmont Country Club in Rockville to claim medalist honors on the first day of the Maryland State Golf Association's 78th annual men's amateur championship.

Doerrer qualified to compete for the title this weekend, which will be decided in a single-elimination match-play format that begins today. The field, which included 130 golfers, was reduced to 32 yesterday. Two rounds will be played today, with quarterfinal and semifinal rounds scheduled for Saturday. The 36-hole championship is Sunday.

Justin Klein, who won last year's championship, automatically qualified for the tournament and elected not to compete for medalist honors yesterday.

Michael Hudek of Towson Golf and Country Club shot a 71 for second. Kirk Lombardi and Wes Gribes were a stroke back.

Nine-time champion Marty West shot a 74, as did Bob Kestner, Chuck Freedman and Henry Blue. Rick Riddle, Brad Hastings, Clark Topping and Mike Albus each shot a 75.

Doerrer, a former member of the DeMatha High School golf team, is the brother of All-Met golfer Steve Doerrer of DeMatha, who won the Washington Catholic Athletic Conference individual championship in May.