Background: Understanding the differences in how patient complexity varies across surgical specialties can inform policy decisions about appropriate resource allocation and reimbursement. This study evaluated variation in patient complexity across surgical specialties and the correlation between complexity and work relative value units. Study design: The 2017 American College of Surgeons National Surgical Quality Improvement Program was queried for cases involving otolaryngology and general, neurologic, vascular, cardiac, thoracic, urologic, orthopedic, and plastic surgery. A total of 10 domains of patient complexity were measured: American Society of Anesthesiologists class 4, number of major comorbidities, emergency operation, major complications, concurrent procedures, additional procedures, length of stay, non-home discharge, readmission, and mortality. Specialties were ranked by their complexity domains and the domains summed to create an overall complexity score. Patient complexity then was evaluated for correlation with work relative value units. Results: Overall, 936,496 cases were identified. Cardiac surgery had the greatest total complexity score and was most complex across 4 domains: American Society of Anesthesiologists class 4 (78.5%), 30-day mortality (3.4%), major complications (56.9%), and mean length of stay (9.8 days). Vascular surgery had the second greatest complexity score and ranked the greatest on the domains of major comorbidities (2.7 comorbidities) and 30-day readmissions (10.1%). The work relative value units did not correlate with overall complexity score (Spearman's r ¼ 0.07; P < .01). Although vascular surgery had the second most complex patients, it ranked fifth greatest in median work relative value units. Similarly, general surgery was the fifth most complex but had the second-least median work relative value units. Conclusion: Substantial differences exist between patient complexity across specialties, which do not correlate with work relative value units. Physician effort is determined largely by patient complexity, which is not captured appropriately by the current work relative value units.