PURPOSE: Inguinal hernias are common in premature infants, but there is substantial variation with regards to timing of repair. We sought to quantify and explain this variation. METHODS: Cohort study of infants <34weeks gestation diagnosed with an inguinal hernia and discharged from one of 329 neonatal intensive units between 1998 and 2012. Multivariable logistic regression clustered by site was used to evaluate demographic, clinical, maternal, and socioeconomic variables associated with pre-discharge repair. RESULTS: A total of 8037 infants met study criteria, and 3230 (40%) received a pre-discharge repair. The frequency of pre-discharge repair varied by site from 9% to 84%, and increased over the study period from 20% in 1998 to 45% in 2012. Concurrent gastrostomy or fundoplication and lower socioeconomic status were associated with an increased odds of receiving a pre-discharge repair. CONCLUSION: There is substantial variation with regards to the timing of repair of inguinal hernias in premature infants, with an increasing number of infants receiving repair prior to hospital discharge over time. Concurrent gastrostomy or fundoplication and socioeconomic status are associated with timing of repair. LEVEL OF EVIDENCE: IV.