One hundred twenty-one patients with acute epididymitis or epididymo-orchitis were evaluated retrospectively according to their clinical symptoms, duration of symptoms, physical examination, and laboratory studies. The patients younger than 30 years of age usually showed less severity of symptoms than the patients older than 50 years of age. The latter often demonstrated evidence of outflow obstruction. Eighty-two percent of patients with demonstrated urographic abnormalities had lower tract abnormalities, mainly secondary to outflow obstruction. All of these patients were older than 50 years of age. An intravenous pyelogram is indicated only in patients over 50 years of age and in young adults with positive bacteriologic urine culture.