Ritter, best known for his role as Jack Tripper on the long-running television sitcom, "Three's Company," would have been 55 next week.
Publicist Lisa Kasteler said in a statement that Ritter was rushed to the hospital after suffering from an unrecognized and undetected flaw in his aorta, CNN reported. She said surgeons were unable to save him.
At the time of his death, Ritter was starring in the ABC sitcom "8 Simple Rules for Dating My Teenage Daughter."
Ritter, youngest son of Western film star and singer Tex Ritter, is survived by his wife, Amy Yasbeck, and their daughter, Stella, and three children -- Carly, Tyler and Jason -- from his first marriage.