During a 2-year period 30 adults were selected out of a group of patients diagnosed with erysipelas, who, except for tinea pedis, were apparently otherwise healthy patients. Clinical and epidemiological studies were performed to establish how tinea pedis and erysipelas are related. Thirteen of 30 patients with a diagnosis of erysipelas were found to have tinea pedis due to Trichophyton mentagrophytes and Trichophyton rubrum. In seven of the patients (23%) tinea pedis was found to be the unique predisposing factor for erysipelas. Tinea pedis may be a risk factor for streptococcal infections such as erysipelas, mainly in tropical countries, where tinea pedis is a frequent disease.