A new approach to endoscopic parathyroidectomy is proposed. Via a 15 mm transverse incision on the anterior border of the sternocleidomastoid muscle (SCM), the fascia connecting the lateral portion of the strap muscles and the thyroid lobe to the carotid sheath is divided at the level of the prevertebral fascia. Once enough space has been created, three trocars are inserted: a 12 mm trocar through the incision and two 2.5 mm trocars above and below the first trocar. Carbon dioxide is insufflated at a pressure of 8 mmHg. Unilateral endoscopic parathyroid exploration is then performed with a 10 mm-0 degree endoscopic camera. Once the adenoma has been identified and, if possible the ipsilateral parathyroid gland, the 3 trocars are removed and the adenoma is extracted from the neck after clipping its pedicle directly through the 15 mm incision. Twenty patients with sporadic primary hyperparathyroidism were operated. The adenoma was localized pre-operatively in 14 patients. Intra-operative quick parathyroid hormone assay was used. Exploration was unilateral in 15 patients--Conversion to transverse cervicotomy was performed in 5 cases. In the 50 explored parathyroid areas, 34 glands (68%) were identified by video surgery: 18 of the 21 enlarged glands (86%) and 16 of the 29 normal glands (55%). Mean operating time was 88 minutes (40'-130'). Morbidity consisted of 2 superficial hematomas in the SCM. With a follow-up ranging from 6 to 15 months, all 20 patients are biochemically cured. This study demonstrates that endoscopic parathyroid exploration can be performed via a lateral incision.