A new case of ovarian seminoma associated with systemic lupus erythematosus is reported. The neoplasia was discovered during a flare-up of lupus. Excision of the seminoma followed by radiotherapy resulted in a 7 1/2-year long remission of systemic lupus erythematosus. This case agrees in every detail with a previously reported case, which suggests a pathogenetic relation between the two diseases. Although this association is rare, clinicians must be aware of its possibility and cautious when confronted with an ovarian abnormality in a young woman with systemic lupus erythematosus.