Epidermoid cyst (monodermal teratoma) of the testis. We report 14 patients with epidermoid cyst of the testis (monodermal teratoma). In 7 patients (5 treated within the last 5 years) the mass was excised and adjacent testicular tissue was biopsied. Seven patients underwent radical inguinal orchiectomy. Carcinoma in situ was not detected in any testicular tissue examined. There was no evidence of tumour recurrence in any patient after a mean follow-up of 10 years. Ultrasonographic appearance was not specific for a diagnosis of epidermoid cyst and exploratory surgery was required in all cases. Excision of the tumour and biopsy of adjacent testicular tissue to determine the presence or absence of carcinoma in situ is adequate treatment for this rare testicular neoplasm. 