Objectives To analyze the role of nurse staffing in improving patient safety due to reducing surgical complications in member countries of Organization for Economic Co-operation and Development (OECD). Methods The number of practicing nurses’ density per 1000 population and five surgical complications indicators including foreign body left in during procedure (FBL), postoperative pulmonary embolism (PPE) and deep vein thrombosis (DVT) after hip and knee replacement, postoperative sepsis after abdominal surgery (PSA) and postoperative wound dehiscence (PWD) were collected in crude rates per 100,000 hospital discharges for age group of 15 years old and over within 30 days after surgery based on surgical admission-related and all admission-related methods. The observations of 21 OECD countries were collected from OECD Health Statistics during 2010-2015 period. The statistical technique of panel data analysis including unit root test, co-integration test and dynamic long-run analysis were used to estimate the possible relationship between our panel series. Results There were significant relationships from nurse-staffing level to reducing FBL, PPE, DVT, PSA and PWD with long-run magnitudes of −2.91, −1.30, −1.69, −2.81 and −1.12 based on surgical admission method as well as −6.12, −14.57, −7.29, −1.41 and −0.88 based on all admission method, respectively. Conclusions A higher proportion of nurses is associated with higher patient safety resulting from lower surgical complications and adverse clinical outcomes in OECD countries. Hence, we alert policy makers about the risk of underestimating the impact of nurses on improving patient safety as well as the quality of health care services in OECD countries.