The 38-year-old Swede failed to advance from the 100-meter butterfly heats Thursday at the London Games, although he still became the first swimmer to compete in six Olympics.
"I'm really happy and pleased with my career even though I'm not pleased at all with my race this morning," Frolander said. "I did some big mistakes — a really bad start, a bad turn and a bad finish — but my swimming was the best it's ever been."
Frolander swam in college in the U.S. at SMU. He has won 57 medals at Olympics, world and European championships — over short and long course. He is confident he won't be at a seventh games in Rio de Janeiro in 2016.
"This is it," he said. "You should never say never, but I don't think so."
His Olympic career began 20 years ago in Barcelona, swimming the anchor leg for Sweden in the 4x200 freestyle relay. He was "terrified" before he dove in with Sweden trailing only the Unified Team. Swimming the last leg for the former Soviets that year was Yevgeny Sadovyi, the 200 free champion.
"I knew I couldn't get too excited, but I kept the Americans away and we got second," Frolander said. "That was a great start."
Frolander won another silver medal with the 4x200 relay team at the 1996 Atlanta Games. Then came his career highlight — gold in the 100 fly at the 2000 Sydney Games. The home favourites, Michael Klim and Geoff Huegill, settled for silver and bronze.
"My dream came true there," he said.
In that same Olympics, Frolander swam in the next lane to Pieter van den Hoogenband when the Dutchman became the first man to break the 48 seconds in the 100 free, finishing in 47.84. That world record stood for nearly eight years until Alain Bernard of France broke it with a now-banned bodysuit.
"When I turned next to him in the semifinal and he was half a body length ahead of me I was like, 'Man, I'm swimming so slow.'" he said. "Then when I touched the finish I did a personal best and I saw his time. I was like, 'Oh, my God, that's quick.'"
Van den Hoogenband is at these games as a TV analyst. Alexander Popov, another of Frolander's old rivals, is presenting medals as an IOC athletes commission member.
"I haven't seen them, but I've got some good memories of competing against them," Frolander said.
Frolander, who is single, has dedicated himself to training at an age when most Olympic swimmers have moved on. He hasn't decided what he'll do in retirement.
"I need some time away," he said. "I love to be involved in my sport in some way, but I don't think it's going to be coaching."
He's one of just two Swedish male swimmers at these games. The women's team has 10, including Therese Alshammar. At 34, she's to compete in her fifth games if she can return for the 50 free after missing her opening events with a pinched nerve in her neck.
Frolander didn't enjoy the high-tech bodysuit era that reached its high point at the 2009 worlds in Rome with 43 world records. But he had begun swimming the 100 fly again, and after the bodysuits were banned his time of 52.3 seconds gave him hope.
On Thursday, his 52.47 left him in 20th place, with only the top 16 making the semifinals. He said he made some "tremendous mistakes."
He then listed everything that went wrong: He dropped his arm at the start; went too long in the turn and had to glide with a kick; made an awkward last stroke at the finish.
"If I can feel I can do under 52 sometime in the future I might come back again because that's something I really want to prove to myself," he said. "But it's hard to motivate yourself when you get older."