This study included 10 patients who had developed mumps orchitis previously and had visited our hospital from January 1997 to November 2007. The present illness, testicular volume and semen analysis of 7 of these patients were retrospectively investigated. Semen analyses and pregnancy statuses were followed up over time. The mean age of the 7 patients was 33 years (range, 21-43 years). Four patients had unilateral (right side) orchitis, and three had bilateral orchitis. In the unilateral orchitis group, 1 patient had an atrophic testis. Findings of semen analysis were severe oligozoospermia in three and mild oligozoospermia in one. None of the patients in the bilateral orchitis group, had atrophic testes. Findings of semen analysis were azoospermia in one and severe oligozoospermia in two patients. Findings of semen analysis in most patients improved gradually, and wives of 2 patients eventually achieved pregnancy. Dysfunction of seminiferous tubules in the diseased testis is thought to be reversible when treated adequately in the initial phase. In the patients not conceiving successfully, testicular sperm extraction (TESE) and assisted reproductive technique (ART) are thought to be effective ways to achieve pregnancy.