Objective: To examine whether baseline model for end-stage liver disease (MELD) score in patients with cirrhosis and ascites predicts the future development of first spontaneous bacterial peritonitis (SBP) episode. Methods: A retrospective case-control study was performed at three academic centers to select patients admitted with first SBP episode (cases) and those with ascites admitted for decompensation without SBP (controls). Medical records from these centers were reviewed between January 1, 2008, and December 31, 2013. Cases and controls were matched (1:2) for age, sex, and race. Conditional logistic recession models were built to determine whether baseline MELD score (within a month before hospitalization) predicts first SBP episode. Results: Of 697 patients (308, 230, and 159 from centers A, B, and C, respectively), cases and controls were matched in 94%, 89%, and 100% at three respective centers. In the pooled sample, probability of SBP was 11%, 31%, 71%, and 93% at baseline MELD scores less than or equal to 10, from 11 to 20, from 21 to 30, and greater than 30, respectively. Compared with MELD score less than or equal to 10, patients with MELD scores from 11 to 20, 21 to 30, and greater than 30 had six- (3- to 11-), 29- (12- to 69-), and 115- (22- to 598-) folds (95% CI) risk of SBP, respectively. Based on different MELD score cutoff points, MELD score greater than 17 was most accurate in predicting SBP occurrence. Analyzing 315 patients (152 cases) with available data on ascitic fluid protein level controlling for age, sex, and center, MELD score but not ascitic fluid protein associated with first SBP episode with respective odds ratios of 1.20 (1.14 to 1.26) and 0.88 (0.70 to 1.11). Conclusion: Baseline MELD score predicts first SBP episode in patients with cirrhosis and ascites.