Sweet's syndrome is an acute febrile neutrophilic dermatosis. Although it frequently appears as an idiopathic disorder, it may occur in association, often as presenting sign, with malignancy or more rarely with infections. We report two cases of Sweet's syndrome preceded by digestive infection due to Yersinia enterocolitica, affirmed by significant rises in serum antibody titers. Other nongastrointestinal manifestations of such infections are known, predominantly arthritis and erythema nodosum. Sweet's syndrome is a rare complication of these infections. Treatment with systemic steroids, usually effective, can be replaced by antibiotics with apparently favorable results. The search of an infectious origin should be systematic in cases of Sweet's syndrome that appear to be idiopathic.