A case of pyogenic vertebral osteomyelitis after acute bacterial prostatitis in a 78-year-old man is reported. The rarity and subtle clinical presentation of this condition, and the delayed appearance of radiologic signs of progression to destructive osteomyelitis, contributed to a significant delay in diagnosis. An arterial blood culture positive for bacterial growth during the episode of acute prostatitis suggested that bacteremia might result from hematogenous spread of the infection to the vertebral column via the venous system. Since intensive antimicrobial therapy proved ineffective, debridement of the first and second lumbar vertebral bodies, and anterior spinal fusion from the twelfth thoracic to the third lumbar vertebrae were performed. The patient's high fever and severe lumbago subsided immediately after the surgery. The possibility of development to pyogenic vertebral osteomyelitis should be kept in mind when treating a serious genitourinary tract infection.