Developmental anomalies arising from the branchial apparatus include cysts, external sinuses, internal sinuses, and complete fistulas. Second branchial cleft cysts are by far the most common among these anomalies. It may occur at any age, being most common in the third decade, and more frequent in the male than in the female. It usually presents a smooth, round, nontender fluctuant mass located between the level of the tragus and the clavicle along the anteromedial border of the sternocleidomastoid muscle. It is lined by respiratory or squamous epithelium unless inflammation is present. The considerable amount of lymphoid tissue may be found beneath the epithelium. The treatment of choice of branchial cleft cyst is surgical excision. If the lesion is acutely infected, however, it is essential to relieve the infection prior to the surgery. This report deals with two cases of second branchial cleft cyst. In case 1, the cyst had rapidly increased in size over pregnant period. In case 2, the patient presented the swelling in the left neck, and had the history of incision and drainage because of misdiagnosis as submandibular space abscess. The infection was treated by antibiotic therapy in the first place, and then complete surgical excision was made. There was no evidence of any recurrence or complications for these 3~4 years.