The Baltimore Orioles lost, 4-3, to the Philadelphia Phillies tonight in the first half of a two-day charity exhibition series, but they showed none of the bitter disappointment that accompanies losing a game during the regular season.

They seemed happy just to be playing.

"That makes me one for one in the National League," joked pitcher Mike Flanagan, who was charged with the loss.

The usually withdrawn Eddie Murray, who homered off Larry Christenson in the third inning, sat by his locker after the game and did more talking than anyone could remember.

"I was a bit surprised," Murray said of the game's only homer. "I'd been hitting balls that weren't quite going out of the ballpark . . . that one felt good . . . it felt pretty good to get back into a game situation."

Both teams came on the second inning. The Orioles took a 1-0 lead when Doug DeCinces doubled, went to third on Rick Dempsey's single and scored on a single by Rich Dauer.

The Phillies came back with two in their half of the inning, loading the bases on Mike Schmidt's single a fielding error by DeCinces and a fielder's choice. One run scored when Larry Bowa grounded into a double play and Bob Boone's single scored another.

DeCinces, who has a sore back and played for only four innings, said he was trying to come back slowly and was grateful not to have played the entire seven-inning game.

"I did so much sitting during those seven weeks," DeCinces said, of his 50-day stint as a negotiator representing the American League players during the baseball strike. "I did better than I expected.

The Orioles went ahead, 3-2, in the third on a walk to Mark Belanger and Murray's homer.

The Phillies took the lead for good with two runs in the fourth off Flanagan, the second of four Baltimore pitchers. Consecutive singles by Gary Matthews, Garry Maddox and Bowa produced one run and Maddox scored on Boone's sacrifice fly.