The case records of 64 patients with 65 episodes of infectious gonarthritis during 1979–88 were reviewed regarding epidemiological, clinical and laboratory data of possible relevance to the course and outcome of the disease. Long-term healing results were evaluated by means of a new scoring system 2–11 years after the acute disease in 46 patients. The infection was acquired by inoculation in 37% and by the hematogenous route in 55%. The major risk factors were trauma to the joint and arthrosis. Staphylococcus aureus was the causative agent in 58% and Streptococci in 15%. Treatment consisted of suction irrigation (86%) or intermittent aspiration (5%) combined with systemic antibiotic treatment. At follow-up, the pain and ache scores of the arthritic joint had decreased by 21% and 16% respectively, compared with the scores of the contralateral control joints. Anatomy and motility were reduced by 9% and 8% respectively. Age < 45 was associated with a greater score loss than in older patients. Treatment delayed by > 5 days was associated with increased loss of motility. We estimate that 79% of the patients had excellent or good long-term results following treatment of infectious arthritis of the knee. Evaluation of healing after infectious gonarthritis by use of a scoring system is quite feasible and allows comparison of different treatment regimes with improved accuracy.