Interscalene brachial plexus block (ISB) using the modified lateral approach provides a well-established method of anesthesia and analgesia for patients undergoing shoulder surgery. Considering the neural anatomy at the site of injection, the superficial cervical plexus may be at risk of injury. We evaluated the incidence and characteristics of superficial cervical plexus neuropathy.During a 1-yr period, 273 consecutive patients requiring single-injection ISB for shoulder or proximal arm surgery were studied. Patients were examined for symptoms compatible with superficial cervical plexus injury before surgery, 24 h postoperatively, and contacted by telephone 31 days after surgery. Symptomatic patients received an additional phone call 6 mo after surgery.Twenty-four hours after shoulder surgery, 21 patients (7.7%) showed symptoms consistent with superficial cervical plexus neuropathy. Symptoms consisted of hypesthesia in 1-4 cutaneous branches of the cervical plexus. Five patients (1.8%) reported symptoms that lasted for >31 days. All symptoms had entirely resolved after 6 mo.Superficial cervical plexus neuropathy is not uncommon after ISB using the modified lateral approach and the possibility should be discussed with patients preprocedurally.