BACKGROUND: Cleft lip represents one of the most common birth defects in the world. Although the timing of cleft lip repair is contingent on a number of factors, the "rule of 10s" remains a frequently quoted safety benchmark. Initially reported by Wilhelmsen and Musgrave in 1966 and modified by Millard in 1976, this rule referred to performing surgery once patients had reached cutoffs in weight, hemoglobin, and age/leukocyte count. Despite significant advances in both surgical and anesthetic technique, the oft-quoted "rule of 10s" has not been systematically investigated since its inception. METHODS: Patients who underwent primary cleft lip repair were identified from the National Surgical Quality Improvement Program Pediatric database. Multivariate logistic regression models were used to determine the independent effect of each rule of 10 metric or violation of the rule of 10s as a whole on postoperative complications, and to determine independent risk factors for complications in cleft lip surgery. RESULTS: One thousand three hundred thirteen patients met inclusion criteria, with a 3.6 percent complication rate. Of the included patients, 151 (11.5 percent) violated at least one facet of the rule of 10s. Other than patient weight, neither the rule of 10s nor any individual metric was significantly predictive of postoperative complications. CONCLUSIONS: Since its introduction nearly a half century ago, the risks associated with performing surgery in patients who violate the rule of 10s has undergone dramatic reductions. This analysis highlights the need to continually validate and evaluate dogma as the field continues to advance. CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, III.