Background: Bowel obstruction is a disorder in the passage of bowel contents, the etiology of which varies depending on temporal and geographical conditions. This study investigated the etiology of bowel obstruction in a large number of patients at an adult surgery referral center in southern Iran. Methods: In this cross-sectional study, we reviewed the medical records of all patients admitted to Shahid Faghihi hospital (Shiraz, Iran) between 2014 and 2020 with a diagnosis of small or large bowel obstruction. Patients with missing or obscure data on etiology were excluded. Data was collected on the patients’ age, gender, history of relevant surgeries, comorbidities, cause of obstruction, site/type of obstruction, treatment, intensive care unit (ICU) admission, length of hospital stay, and outcome. Statistical analyses were made using SPSS v. 25.0. Results: A total of 2781 bowel obstruction patients (61.4% males, 38.6% females) with a median age of 58 (IQR 43-71) years were studied. Most responded to non-surgical treatment (61.3%). While the obstruction was mostly partial (65.5%), 94.4% of patients with complete obstruction required surgery. Small bowel obstruction (SBO) was almost three times more prevalent than large bowel obstruction (LBO). Adhesion bands were the leading cause of SBO (66.77%), while LBO was primarily due to colorectal tumors (33.9%). Conclusion: The predominant etiology of LBO was colorectal cancer, suggesting that policymakers should improve surveillance programs to detect the condition earlier. Regarding SBO, the leading cause was adhesion bands, indicating the necessity of further efforts to reduce the rate of adhesions following intra-abdominal operations.