Infection of a total knee arthroplasty with Streptococcus bovis in a 76-year-old man that led to the diagnosis of a bowel carcinoma is reported. Investigation revealed a malignancy in the ascending colon with extension into the adrenal gland. S bovis in conjunction with colonic neoplasia has been reported in several orthopedic conditions: vertebral osteomyelitis, discitis, lateral neck abscess, and osteomyelitis of the ileum. The relationship of S bovis to endocarditis, meningitis, brain abscesses, and peritonitis has also been well described. However, S bovis is a rare pathogen infecting joint prostheses and should raise the possibility of a gastrointestinal lesion.