Dorin failed to make weight for his Saturday championship defence in Bucharest, Romania, against Panama's Miguel Callist. The fight was cancelled after Dorin weighed in 4.4 pounds over the 135-pound lightweight limit.
"Leonard declared he no longer wanted to box, and that he was terminating his boxing career," Interbox said in a statement.
"I am in a very, very bad situation," Dorin said before the weigh-in. "I feel sick. I can't take it anymore, I've been in a very difficult training program and I think it was too much for me."
Leonard Dorin, seen in this file photo, reportedly retired from boxing Friday. (CP Photo)
Dorin agreed to fight Callist on Saturday with no title on the line, but that fight was called off when Callist collapsed during an interview with Romanian television. Had Callist won that fight, he would have won the belt as stipulated by WBA rules.
The title is now vacant.
The 33-year-old Dorin is promoted by Montreal-based Interbox. He currently lives in Montreal and is a national hero in his native Romania.
Dorin, whose real name is Leonard Doroftei, fought for 13 years as an amateur in Romania before turning pro with Interbox in 1998.
He has held the WBA belt since defeating Argentina's Raoul Balbi on Jan. 5, 2002.
Dorin fought to a draw against International Boxing Federation (IBF) lightweight king Paul Spadafora in May. It was the only professional bout in which he did not record a victory.
with files from Canadian Press