OBJECTIVES: Cleft lip with and without cleft palate is the second most prevalent birth defect in the United States. Previous epidemiological studies of cleft lip surgery have been plagued by multiple design and methodological issues, including failure to adjust costs, grouping of cleft lip only (CL) with cleft lip and palate (CLP) diagnoses, and improper definition of secondary cleft lip surgery. The objective of this study was to provide national estimates of primary and secondary cleft lip surgery using cohort definitions based on national treatment guidelines. METHODS: The nationally representative Kids’ Inpatient Database (KID) was used for this study. Years analyzed included 2003, 2006, and 2009. Subjects were identified by International Classification of Diseases Ninth Revision (ICD-9) diagnosis of cleft lip only or cleft lip and palate. Primary surgery was defined as a surgery before two years of age with the ICD-9 procedural code for cleft lip repair. Secondary surgery was defined as a surgery at age two or older with the ICD-9 procedural code for cleft lip repair. Additional characteristics examined across cohorts include length of stay and Consumer Price Index (CPI) adjusted charges. RESULTS: A total of 8,385 discharges for cleft lip repair were reported. In CL patients secondary surgery represented 16.3% (N=134), 14.2% (N=105), and 15.1% (N=129) of surgeries for 2003, 2006, and 2009, respectively. In CLP patients secondary surgery represented 25.7% (N=511), 25.2% (N=506), and 28.2% (N=555) for 2003, 2006, and 2009, respectively. From 2003-2009, mean length of stay and CPI-adjusted costs decreased in all cohorts except secondary surgery in CL patients. CONCLUSIONS: One fourth of all children required secondary surgery.  The proportion of secondary cleft lip surgery did not differ significantly across years. Once adjusted, costs have decreased for the majority of patients, a finding in contrast to previously published studies.