OBJECTIVE: This prospective cohort study explored factors related to postoperative pain in gastric cancer patients. METHODS: A total of 236 patients who underwent gastrectomy were enrolled. All patients enrolled in the study completed the Hospital Anxiety and Depression Scale (HADS) questionnaire and Life Orientation Test-Revised (LOT-R) questionnaire on the day before surgery. Heat pain threshold (HPT), cold pain threshold (CPT) and pressure pain threshold (PPT) were measured for all patients one day prior to surgery and demographic details were collected. All patients were connected to a patient-controlled intravenous analgesia (PCIA) pump at the end of the surgery. The occurrence of postoperative pain was used as a dependent variable, and multivariate logistic regression analyses were conducted to screen for factors affecting postoperative pain. RESULTS: In total, 83 patients (35.2%) had postoperative pain. Body mass index (BMI) ≥28 kg/m [odds ratio (OR): 2.67; 95% confidence interval (95% CI): 1.07-6.67], total gastrectomy (OR: 2.64; 95% CI: 1.42-4.91), preoperative anxiety score ≥8 (OR: 2.37; 95% CI: 1.12-5.02), heat pain threshold ≤4.9 s (OR: 2.14; 95% CI: 1.06-4.32), pressure pain threshold ≤4 g (OR: 2.05; 95% CI: 1.05-4.03), and female gender (OR: 1.99; 95% CI: 1.04-3.83) were risk factors for postoperative pain. CONCLUSIONS: Obesity, wide range of gastrectomy, high preoperative anxiety, low HPT and PPT, and female gender are associated with increased risk for postoperative pain.