Testicular cysts are increasingly diagnosed in the course of scrotal ultrasound examination. Among other things this is due to the general availability of modern high-resolution ultrasound devices. Benign and malignant diseases with testicular cyst formation need to be differentiated by differential diagnosis and by their aetiology. Benign diseases with cystic space-occupying lesions of the testicle are tubular ectasia of the rete testis, cystic dysplasia, epidermoid cysts, simple intraparenchymatous testicular cysts and cysts of the tunica albuginea. Testicular dermoid cyst was long misleadingly regarded as potentially malignant, but is now classified as benign. On diagnosis of a benign lesion of the testis an organ-conserving surgical therapy or an observational watch-and-wait strategy can be recommended in most cases.