The cause was liver cancer, his brother Kevin said.

Dokes, who was known by the nickname Dynamite, aspired to a larger-than-life persona, wearing fedoras and mink coats, and entering the ring blowing kisses and tossing roses to women in the crowd. He claimed to have bathed in $20,000 worth of Champagne.

But his career was a roller coaster of ups and downs remarkable even for his rough-and-tumble sport. His mother pushed him toward boxing to stop him from fighting on the streets of Akron, and he won national amateur heavyweight titles as a teenager. In 1977, at 18, he fought a 35-year-old Muhammad Ali in a highly publicized exhibition match in Miami, and in 1982, at 24, he scored a technical knockout of Mike Weaver in just over a minute in Las Vegas to win the World Boxing Association heavyweight crown.

He lost the title nine months later to Gerrie Coetzee, and later confessed that he had used cocaine less than 48 hours before the fight. He was convicted of at least three charges of drug possession and trafficking, and was in and out of narcotics rehabilitation programs. Boxing Insider quoted him saying that he once trained for a fight on "Jack Daniel's and cocaine."

He compiled a 53-6-2 professional record with 34 knockouts. Some of his fights won high praise. Ring magazine called his 1989 bout with Evander Holyfield, who scored a technical knockout in the 10th round, the best heavyweight battle of the 1980s. Holyfield said Dokes's hands were the swiftest he had encountered.

Other fights were disasters. In a title bout against Riddick Bowe in 1993 at Madison Square Garden (the gate receipts of $1.4 million set a Garden record), Dokes was beaten so brutally in the first round that the referee stopped the fight. Dokes had downed a huge plate of pasta before the match, The Plain Dealer of Cleveland reported.

"The past is history, the future isn't here yet, and the present is linguine and clam sauce," he told the newspaper.

Michael Marshall Dokes, the son of a boxer, was born on Aug. 10, 1958, in Akron, where he grew up. He was runner-up for the Amateur Athletic Union and the Golden Gloves titles in 1974 before winning the A.A.U. title in 1975 and the Golden Gloves in 1976.

In the 1975 Pan American Games, he lost a 3-2 decision to Teófilo Stevenson, the powerful Cuban heavyweight who died in June. Dokes's amateur record was 147-7, including victories over the future heavyweight champions John Tate and Greg Page.

Dokes, who was 6 feet 3 inches and had a 78-inch reach, never won a fight as a heavyweight champion. His rematch with Weaver was scored a draw, meaning that he kept the title.

In 2000, three years after his retirement from boxing, he pleaded guilty in a Nevada state court to attempted murder, second-degree kidnapping and intent to commit sexual assault for attacking Sandra Kaye Cummings, his girlfriend of more than nine years. Her injuries, which included a broken nose and cheekbone, were so severe, the police said, that she could not be recognized in a driver's license photograph. He was sentenced to 10 years, and after being paroled in 2008 he returned to Akron.

In addition to his brother Kevin, Dokes is survived by his sister, Alisa Dokes Williams, and his brothers Steven and Charles.