He went to Germany twice in 2011 for a procedure on his sore right knee and a sore left ankle that bothered him at the time.
The Los Angeles Times on Thursday cited people with knowledge of the situation as saying that Bryant was going to Germany this time. He was having a knee procedure that involves removing blood from the affected area and spinning it in a centrifuge. Molecules that cause inflammatory responses are then removed to create a serum that is injected back into the affected area.
Lakers coach Mike D'Antoni told the Times that Bryant's trip and ensuing procedure had been planned, and that the team had no concerns about it.
The 35-year-old guard has been recovering from his Achilles injury and subsequent surgery. He did some shooting at training camp on Wednesday, but hasn't been cleared for running or jumping.
The Lakers haven't provided a timetable on Bryant's return from the Achilles injury other than saying in April that he would be back in six to nine months. The overseas procedure won't affect his recovery time from the tendon injury.
The Lakers open the season Oct. 29 against the Clippers.