AbstractThis report provides a detailed description of the operative technique, anatomical variations, and surgical pitfalls of supraclavicular upper dorsal sympathectomy for palmar hyperhidrosis, based on experience with performance of a simultaneous bilateral operation in 155 patients between 1971 and 1976. The denervation is preganglionic and is confined to removal of T2 and T3 ganglia. Frozen section examination of the specimen is useful in preventing technical failure. Persistent Horner's syndrome occurred in 8% of the patients and is the main complication of the procedure. The advantages of the supraclavicular approach are ease of performing a bilateral procedure, few pulmonary complications because of the extrapleural approach, minimal overall morbidity, and good results in relieving palmar hyperhidrosis.