A case of appendicitis followed by reactive arthritis in an HLA B27-positive, 29-year-old man after infection with Yersinia enterocolitica is reported. Infection with Y. enterocolitica was diagnosed by determination of serotype specific antibodies and antibodies to Yersinia outer membrane proteins. Bacteriological cultures from the appendix were not made. Although reactive arthritis is a well-known complication of Yersinia-associated enteric disease, there are only few reports of patients with Y. enterocolitica pseudo-appendicitis complicated by arthritis during follow-up.