Dissertation (MMED General Surgery)Postoperative pains the most common complaint by patients after recovery from anesthesia. Several factors cause postoperative pain, it could be preoperative factors, demographic factors, anesthesiologic factors, intraoperative and postoperative factors. The prevalence of postoperative pain is very high in most of the developing countries and the strategies put forward for management have not been very promising. This study aimed to determine the prevalence, progression, severity, and predictors of postoperative pain among adultsadmitted atthe surgical wards in Iringa Regional Referral Hospital from June to September 2019. A hospital-based prospective longitudinal study that included 166 postoperative patients from the surgical wards of Iringa Regional Referral Hospital from June to September 2019. A consecutive sampling technique was employed to recruit study participants. The patients were followed up for 48 hours postoperatively. Data analysis was done using Statistical Package for Social Science v.25. Logistic regression analysis was used to calculate the association between dependent and independent variable. A total of 166 patients were recruited with a mean age of 42.01 ±17.2 (Range=18-78). The prevalence of postoperative pain was 80.4%, 71.1%, 59%, 32.5%, 8.4% and 2.4% at 8, 16, 24, 32, 40, and 48 hours respectively. The majority of the patients complained of mild to moderate pain during the first 8 hours postoperatively, and significant patients with moderate pain had shifted to mild pain within the first 16 hours postoperatively. The main predictors of postoperative pain within the first 8 hours postoperatively were the duration of surgery being > 2 hours (AOR=47.8, P=0.001), female gender (AOR=6.165, P=0.005), younger age (AOR=3, P=0.049), and orthopedic procedures (AOR=7.3, P=0.02). Post-operative pain prevalence is high within the first 24 hours. The multimodal approach ensured that none of the patients had severe pains and beyond. Efforts to address post-operative pain experienced during the first 24 hours are urgently needed. Orthopedic procedures, increased duration of the procedure, younger age, and female gender were the main predictors of postoperative pain.