Background/Aims: Postoperative complications tend to occur in high-risk populations, including those undergoing major surgery.Surgical site infections (SSI) are some of the most common postoperative complications in laparotomy procedures. Surgery induces a postoperative stress response, triggering an inflammatory process that increases muscle protein proteolysis. Preoperative protein intake increases muscle protein reserves and supports postoperative wound healing and immunity. This study analyzed the association between preoperative protein adequacy and post-elective laparotomy SSI. Methods: A prospective cohort study was conducted on 93 subjects with an adequate protein group of 48 subjects and an inadequate protein group of 45 subjects undergoing elective laparotomy at Dr. Cipto Mangunkusumo Hospital, Jakarta. The protein adequacy was analyzed using an interview method for seven days preoperatively. Patient monitoring was carried out for 30 days postoperatively to assess the complications in the form of SSIs. The association between protein adequacy and SSI was analyzed using a Chi-Square test, and multivariate analysis was performed to assess the factors most associated with post-elective laparotomy SSI. Results: An association was observed between preoperative protein adequacy and post-elective laparotomy SSI (RR 3.413; 95% CI, 1.363–8.549; p=0.004). Multivariate analysis showed that the preoperative protein adequacy and preoperative albumin levels were strongly predictive of the occurrence of SSI. Conclusions The preoperative protein adequacy and albumin levels were strongly related to predicting the post-elective laparotomy SSI.