"I'm back," Numminen told The Associated Press as he arrived at HSBC Arena with his equipment bag and two sticks during the Sabres full-team practice. Numminen said he would practice on his own later in the day.
Coach Lindy Ruff said the team's training staff is evaluating Numminen's condition, but it was too early to determine whether he would be cleared to play before the end of the regular season.
The Sabres, who host Tampa Bay on Wednesday, have nine games left over the final three weeks of the season and are trying to climb back into playoff contention. Coming off two straight wins, Buffalo has crept to within a point of Philadelphia, which holds the eighth and final playoff spot in the Eastern Conference.
Numminen's return is on track with the timetable Sabres doctors gave him in January when he rejoined the team. Though not cleared for contact, Numminen began skating with the Sabres in hopes he could resume playing in February.
But doctors told the 39-year-old he would have to rest until the middle of March to allow his sternum to fully heal.
Numminen had surgery at the Cleveland Clinic in September to repair a faulty valve that was discovered during a routine checkup as he was preparing to report to training camp for his 19th NHL season, and third with Buffalo.
The Finnish player has had a heart murmur since childhood and was diagnosed with a dilated aorta in March 2004, when he was playing for the Dallas Stars. Numminen missed five games because of the condition before he was cleared to play.
The condition also forced him to miss one game and part of another during a playoff series against Philadelphia in 2006.
Numminen also had ankle surgery in January to remove a bursa sac that had been bothering him over the past couple of seasons.
Numminen re-signed with the Sabres to a one-year, $2.6 million contract in July. But he's spent the season on the team's suspended list, so his contract doesn't count against the salary cap.