Small bowel obstruction (SBO) frequently necessitates emergency surgical intervention. The impact of frailty and age on operative outcomes is uncertain. This study evaluated postoperative outcomes of SBO surgery based on patient's age and frailty and explore the optimal timing to operation in elderly and/or frail patients. Patients who underwent SBO surgery were identified in ACS-NSQIP database 2005-2021. Patients aged ≥65 years were defined as elderly. Patients with 5-Factor Modified Frailty Index≥2 were defined as frail. Multivariable logistic regression was used to compare 30-day post-operative outcomes between elderly frail versus non-frail patients, as well as between non-frail young versus elderly patients. 49,344 patients had SBO surgery, with 7,089 (14.37%) patients classified as elderly frail, 17,821 (36.12%) as elderly non-frail, and 21,849 (44.28%) as young non-frail. Elderly frail patients had higher mortality (aOR = 1.541, p < .01) and postoperative complications compared to their elderly non-frail counterparts; these patients also had longer wait until definitive operation (p < .01). Among non-frail patients, when compared to young patients, the elderly had higher mortality (aOR = 2.388, p < .01) and complications, and longer time to operation (p < .01). In elderly non-frail patients, a higher mortality was observed when surgery was postponed after 2 days. Mortality risk for frail elderly patients is heightened from their already higher baseline when surgery is delayed after 4 days. When SBO surgery is postponed for more than 2 days, elderly non-frail patients have an increased mortality risk. Consequently, upon admission, these patients should be placed under a nasogastric tube and undergo an initial gastrograffin challenge. If there is no contrast in colon, they should be operated on within 2 days. Conversely, elderly frail patients with SBO have a higher mortality risk when surgery is delayed beyond 4 days. Thus, following the same scheme, they should be operated on before 4 days if gastrograffin challenge fails. Retrospective Cohort Study, Level III.