The game never got underway and was called after a delay of more than two hours. No makeup date was immediately set.
The rainout gave Baltimore manager Lee Mazzilli the opportunity to skip injured Bruce Chen's turn in the starting rotation. Chen was scheduled to pitch Thursday in the opener of a four-game series against Cleveland, but his status was in doubt because of a hyperextended left big toe.
Rookie right-hander Hayden Penn, who was supposed to start Wednesday, was pushed back to Thursday. Rodrigo Lopez will start Friday, followed by Daniel Cabrera and Sidney Ponson.
"Then we'll see what happens Monday," Mazzilli said.
The postponement also provided third baseman Melvin Mora another day to rest his strained right hamstring. Mora has not played since June 21, but is close to making a return.
"Being banged up, this gives a chance to come back and go with our first string," Mazzilli said.
Yankees manager Joe Torre shuffled his rotation for the three-game series in Detroit that begins Friday. Mike Mussina, who was scheduled to start Wednesday despite feeling ill, was pushed back to Saturday. Randy Johnson will pitch Friday on regular rest, and Carl Pavano will start Sunday instead of Chien-Ming Wang.
"It would've been tough tonight," Mussina said. "We're in a tight spot. We're a little short on starters and I told them I'd do whatever I could do. If that was three or five (innings), I didn't know, but I'd do what I could do.
"Now, with the rainout, that kind of helps us. We'll just fit back in here on the weekend."
Torre would have preferred that the game be played, but after the delay extended past the two-hour mark, he was happy with the washout.
"You certainly don't need a day off before you have a day off," he said, "but as long as we had to wait, I'd just as soon they do this as opposed to being out here until 2 in the morning, which would've negated the other off-day."
Penn, meanwhile, was disappointed at missing an opportunity to pitch against Mussina and the Yankees.
"I was excited to throw tonight, looking forward to it," he said. "Mussina is a great pitcher, and I would have loved to have said we faced up."
The Yankees have one more series in Baltimore, from Sept. 27-29. Both teams have Sept. 26 off, making that a possible makeup date.
It was the second rainout for the Orioles this season. They had nine last year.