A 6-month-old boy was referred to our hospital with left scrotal swelling. Scrotal ultrasound examination revealed a 2 cm cystic mass without solid component in left testicular parenchyma. Serum AFP, hCG and LDH levels were within normal limits. Although we suspected a simple cyst of the testis or a benign testicular tumor, the left testicle was explored via an inguinal incision in case of malignancy. Since intraoperative frozen section revealed benign, we preserved the remaining testis. The wall of cystic mass had a small solid lesion. The definitive pathological examination of the cyst wall showed mature teratoma including squamous epithelium, glandular epithelium of enteric type and cartilage. At 4 years of follow up, he was free of recurrence without testicular atrophy.