Septic arthritis in the elderly carries a high mortality. Underlying risk factors, such as diabetes, malignancy, chronic renal failure, rheumatoid arthritis, hepatobiliary disease and AIDS, should be assessed. Rare causative organisms are occasionally encountered. Here, we describe a case of an 80-year-old diabetic patient with liver cirrhosis who developed Klebsiella pneumoniae septic arthritis, which is a rare cause of joint infection. We postulate that this case supports the notion that the patient's knee effusion seeded during a primary K pneumoniae bacteraemia of intestinal origin and related to liver cirrhosis.