Tommy Leonetti, 50, a popular singer with bands and in television in the 1950s, died of cancer Saturday at St. Joseph Hospital in Houston.

A resident of Los Angeles, where he owned a recording studio, Mr. Leonetti had been under treatment at the hospital for about two years. He had appeared recenlty on television in behalf of the hospital's nonprofit Stehlin Foundation for Cancer Research.

In 1958-59, Mr. Leonetti appeared on NBC'S "Your Hit Parade" with such other young stars as Jill Corey, Virginia Gibson and Alan Copeland.The show moved to CBS and he was without a job.

He ran into further bad luck when a witness before a Senate Labor Rackets Committee, investigating racketeering in the juke box business, said that Mr. Leonetti's manager had used an implied threat of violence to push his records.

Mr. Leonetti offered to testify before the committee but was cleared of any involvement before he was called. As a result of the publicity, however, he was in big demand, and went on to plug a best-selling record, "Moonlight Serenade."

Mr. Leonetti was born in New Jersey. He was a former singer with the Tony Pastor and Charlie Spivak bands. He lived in Australia during the late 1960s and early 1970s, where he became a popular television star.