Background: The surgical Apgar score (SAS) has demonstrated utility in predicting postoperative outcomes in a variety of surgical disciplines. However, there has not been a study validating the utility of the SAS in surgical patients in low-income countries. We conducted a prospective, observational study of patients undergoing laparotomy at a tertiary referral hospital in Rwanda and determined the ability of SAS to predict inpatient major complications and mortality. Methods: All adult patients undergoing laparotomy in a tertiary referral hospital in Rwanda from October 2014 to January 2015 were included. Data were collected on patient and operative characteristics. SAS was calculated and patients were divided into four SAS categories. Primary outcomes were in-hospital mortality and major complications. Rates and odds of in-hospital mortality and major complications were examined across the four SAS categories. Logistic regression modeling and calculation of c-statistics was used to determine the discriminative ability of SAS. Results: 218 patients underwent laparotomy during the study period. One hundred and forty-three (65.6%) were male, and the median age was 34 years (IQR 27–51 years). The most common diagnosis was intestinal obstruction (97 [44.5%]). A high proportion of patients (170 [78%]) underwent emergency surgery. Thirty-nine (18.3%) patients died, and 61 (28.6%) patients had a major complication. In-hospital mortality occurred in 25 (50%) patients in the high-risk group, 12 (16%) in the moderate-risk group, 2 (3%) in the mild-risk group and there were no deaths in the low-risk group. Major complications occurred in 32 (64%) patients in the high-risk group, 22 (29%) in the moderate-risk group, 7 (11%) in the mild-risk group and there were no complications in the low-risk group. SAS was a good predictor of postoperative mortality (c-statistic 0.79) and major complications (c-statistic 0.75). Conclusions: SAS can be used to predict in-hospital mortality and major complications after laparotomy in a Rwandan tertiary referral hospital.