MUMPS ARTHRITIS is an unusual complication of a common disease. Hippocrates,1 in the fifth century BC, first described the typical features of nonsuppurative swelling behind the angle of the jaw occasionally followed by orchitis. In 1850, Rettier2 first mentioned arthritis rapidly following mumps in two brothers. Maisondieu2 attempted to calculate the frequency of arthritis during the Paris mumps epidemic of 1923-1924 and in 1,334 cases he noted six with arthritis, an incidence of 0.44%. The present article reports a case of migratory polyarthralgia associated with mumps and delineates the clinical features of mumps arthritis by reviewing previously reported cases. Report of a Case A 17-year-old white male high school student entered the Womack Army Hospital, Fort Bragg, NC, on Oct 2, 1964, because of right testicular swelling of one day's duration. At the age of 2 months he had undergone thymic irradiation because of respiratory difficulty. A right inguinal herniorrhaphy