Introduction: The Russian invasion of Ukraine has caused huge damage to all medical infrastructure and impairs patient safety. The aim of our study was to assess the impact of implementation of the WHO Surgical Safety Checklist and Anesthesia Equipment Checklist on patient outcomes and adherence to safety standards in low-resource settings, affected by an ongoing war., Material and Methods: A prospective multicenter study was conducted in 6 large Ukrainian hospitals. The study was conducted in two phases: a control period, lasting five months, followed by a study period, when the two checklists (the WHO Surgical Safety Checklist and Anesthetic Equipment Checklist) were introduced in the designated operating rooms. The primary outcomes were any major complications, including death, during 30 days after surgery., Results: A total of 2237 surgical procedures were recorded - 1178 in the control group and 1059 in the intervention group. Major postoperative complications occurred in 82 (6.9%) patients in the control group and in 25 (2.4%) in the study group (OR = 0.32 [0.19-0.52], P < 0.001). The effect on the incidence of specific postoperative complications was statistically significant for the "surgical infection" (1.5% vs. 0.1%; OR = 0.31 [0.1-0.8], P = 0.01) and "reoperation" (1.7% vs. 0.5%; OR = 0.32 [0.1-0.8], P = 0.01) cate-gories as well as for the 30-day mortality (1.3% vs. 0.3%; OR = 0.35 [0.1-0.9], P = 0.03). Better adherence to basic WHO surgical safety recommendations was observed for every check mentioned in the WHO Surgical Safety Checklist ( P < 0.05)., Conclusions: The WHO Surgical Safety Checklist and the Anesthesia Equipment Checklist improve patient outcomes in war-affected low-resource settings.