The definition of a peritoneal catheter exit site infection varies from one dialysis center to another. A review of abnormal appearing exit sites (n = 334 in 169 patients) from 1/83 to 3/91 was done to compare outcome in exit sites presenting with erythema (39, 12%) to those with drainage plus erythema (72, 22%) or drainage alone (223, 67%). Resolution of the abnormality occurred in 48% of those exit sites with drainage, 62% with erythema and drainage, and 79% with erythema alone (p < 0.005). S. aureus was present in 62% of the cultured exit sites which had erythema alone, 64% with erythema plus drainage, and 41% with drainage alone, while Gram negative rods were present in 13%, 12%, and 35%, respectively (p < 0.005). Twenty-three of the 39 exit sites with erythema were not initially treated with antibiotics; 87% resolved compared with 69% of those treated immediately with antibiotics (p = ns). Seven of the 8 erythematous exit sites that did not resolve progressed to tunnel infection and/or peritonitis and required catheter removal, despite the addition of antibiotics in the three initially untreated. Six of the 8 unresolved erythematous exit sites were due to S. aureus. These results indicate that, although drainage is the commonest exit site abnormality and has the worst prognosis, peri-catheter erythema is not always benign, representing an early sign of infection in some cases.