Background: Classical teaching advocates watchful waiting for 2 days before operating on adhesive-related intestinal obstructions (AIOs). Our aim was to compare the clinical and cost outcomes of early versus late adhesiolysis for AIOs. Design: Patients undergoing adhesiolysis for AIOs from the 2007 Nationwide Inpatient Sample were stratified to early (≤2 days from admission) vs. late (>2 days) adhesiolysis. The primary outcome was in-hospital mortality and secondary outcomes were post-operative complications (POCs), post-operative length of stay (PLOS), and in-hospital cost. Results: From 5,443 patients who underwent adhesiolysis for AIOs, 53 and 47 % underwent early and late adhesiolysis, respectively. Late adhesiolysis patients were older (65.0 vs. 60.1 years) and more co-morbid compared to the early group (p < 0.05). After adjustment with propensity score methods, late adhesiolysis patients had no difference in mortality (odds ratio [OR] 0.95, 95%-confidence intervals [CI] 0.67-1.36, p = 0.79) or POCs (OR 1.01, 95%CI 0.89-1.14, p = 0.91) compared to the early group, but had 9.8 % increased PLOS and 41.9 % increased in-hospital cost (p < 0.001). Conclusions: The 2-day limit of watchful waiting is not associated with increased mortality or POCs for those patients undergoing adhesiolysis for an AIO. Late adhesiolysis, however, was associated with significantly increased PLOS and in-hospital cost compared to early adhesiolysis. © 2012 The Society for Surgery of the Alimentary Tract.