Current protocols for the management of abdominal stab wounds were established based on retrospective data from prior decades. Few have investigated whether higher body mass index (BMI) affects outcomes after these injuries.The aim was to determine the effects of obesity on outcomes in abdominal stab wound patients.This was a retrospective cohort study at a Level I university-associated trauma center in the United States.We reviewed medical records of 100 adult patients admitted to our trauma center with abdominal stab wounds. Demographics, types of internal organ injury, gastrointestinal (GI) resection and repair, mortality, length of hospital stay (LOS), units of blood transfused within 24 h of admission, need and indications for exploratory laparotomy, surgical site infections (SSI), and need for re-operation were compared between obese and nonobese patients.Categorical and continuous outcome variables were compared between the two groups using Chi-squared and independent-samples t-tests, respectively. BMI was evaluated as a predictor of outcomes using univariate and multivariate logistic regression.Records of 100 adult abdominal stab wound patients were reviewed. Twenty-five patients were obese. The obese group was older (38.76 vs. 31.23, P = 0.018). Rates of therapeutic laparotomy were similar between obese and nonobese patients (20 [80.00%] vs. 64 [85.33%]). Obesity was associated with longer LOS (9.6 vs. 6.5, P = 0.026). In the multivariate analysis, increasing BMI was an independent predictor of need for GI resection (odds ratio: 1.10 [1.02-1.18], P = 0.018). One patient from the obese group died.Obese patients with abdominal stab wounds have longer LOS than nonobese patients. Increasing BMI was an independent predictor of need for GI resection.