BACKGROUND Patients undergoing thoracoscopic procedures may be at high-risk for incomplete neuromuscular recovery and associated complications. The aim of this clinical investigation was to assess the incidence of postoperative residual neuromuscular blockade in adult thoracic surgical patients administered neostigmine or sugammadex when optimal dosing and reversal strategies for these agents were used. The effect of choice of reversal agent on hypoxemic events and signs and symptoms of muscle weakness were also determined. Additionally, operative conditions in each group were graded by surgeons performing the procedures. METHODS Two hundred patients undergoing thoracoscopic surgical procedures were enrolled in this nonrandomized controlled trial. One hundred consecutive patients maintained at moderate levels of neuromuscular blockade were reversed with neostigmine (neostigmine group) followed by 100 consecutive patients given sugammadex to antagonize deeper levels of neuromuscular blockade (sugammadex group). Anesthetic and neuromuscular management were standardized. Surgeons rated operative conditions at the conclusion of the procedure on a 4-point scale (grade 1 = excellent to grade 4 = poor). Train-of-four ratios were measured immediately before extubation and at PACU admission (primary outcomes). Postoperatively, patients were assessed for adverse respiratory events and 11 signs and 16 symptoms of muscle weakness. RESULTS The 2 groups were similar in intraoperative management characteristics. The percentage of patients with residual neuromuscular blockade, defined as a normalized train-of-four ratio