BACKGROUND: Acute kidney injury (AKI) is common in preterm infants, but specific therapies remain scarce. Recent studies have demonstrated an association between caffeine exposure and less frequent AKI in the first 7-10 days after birth. We hypothesized that patients with necrotizing enterocolitis (NEC) and spontaneous intestinal perforation (SIP) would provide a better natural model of AKI to evaluate this association. METHODS: We reviewed all premature patients diagnosed with NEC or SIP at our institution from 2008 to 2014. AKI was defined by change in serum creatinine using the neonatal Kidney Disease: Improving Global Outcomes definition. Caffeine was prescribed for apnea of prematurity and caffeine exposure was determined by chart review. RESULTS: A total of 146 patients with NEC/SIP were reviewed. Of these, 119 (81.5%) received caffeine, and 91 (62.3%) developed AKI. AKI occurred less frequently in patients who received caffeine than in those who did not (55.5% vs. 92.6%; odds ratio (OR) 0.10; 95% confidence interval (CI) 0.02-0.44). This association persisted in multivariable models after adjustment for potential confounders (adjusted OR 0.08; 95% CI 0.01-0.42; number needed to be exposed to caffeine to prevent one case of AKI = 2.6). Although baseline serum creatinine did not differ by caffeine exposure, patients receiving caffeine had lower peak creatinine (median 1.0 mg/dl vs. 1.5 mg/dl; p = 0.008) and absolute creatinine change (median 0.42 mg/dl vs. 0.68 mg/dl; p = 0.003) than those who did not. CONCLUSIONS: Caffeine exposure in preterm infants with NEC/SIP is associated with decreased incidence and severity of AKI.