The three-time All-Star, who had arthroscopic surgery on both knees a little more than three weeks ago, worked out for about a half-hour with his teammates on Wednesday. He said afterward that he did not have any pain.
"It felt good to be back out there on the floor," said Roy, who has said that the problem with his knees is too little cartilage.
Blazers coach Nate McMillan said Roy will be eased back into the rotation and his minutes will be closely watched. There is no timetable for Roy to start playing again.
"We will work him in and make adjustments for what he can do on the floor," McMillan said.
Roy had said earlier this week that he wanted to play this Friday when the Blazers visit Toronto.
"Maybe I got a little ahead of myself there," Roy said.
Roy is averaging 16.6 points in 23 starts this season. In his absence the Blazers have run their offense through LaMarcus Aldridge, who is averaging 25.4 points and 10.2 rebounds since Dec. 15.
Blazers center Marcus Camby, who also had arthroscopic surgery last month, also returned to practice. He too was limited to 30 minutes.
Camby was averaging 5.9 points and 11.3 rebounds in 39 games this season.
The return of Roy and Camby was encouraging for the Blazers, who have been dogged by injuries for the second straight season.
In November, the team announced that center Greg Oden, the No. 1 draft pick in 2007, would miss the season because of microfracture surgery on his left knee. Oden missed his rookie year because of microfracture surgery on his right knee.
Second-year forward Jeff Pendergraph injured his knee in the preseason and required season-ending surgery. And rookie guard Elliot Williams has undergone surgery this season on both knees.
Last season, Roy had arthroscopic surgery to repair the meniscus in his right knee two days before the Blazers opened their first-round playoff series against Phoenix. He made a remarkable comeback and played in the fourth game of the series, which the Suns eventually won, but some have suggested he might have returned too soon.
Roy said he accepts McMillan's caution.
"I feel good but at the same time I understand where he's coming from," Roy said. "He wants me to feel great."