Background: Most of previous studies aimed to estimate the effect of nurse staffing on quality of acute hospital care have used stochastic methods and their results are mixed.Objective: To measure the magnitude of effect of nurse-staffing level on increasing quality of acute care services in long-run.Data: The number of practicing nurses’ density per 1000 population as the proxy of nurse-staffing level and three Health Care Quality Indicators (HCQI) included 30-day mortality per 100 patients based on acute myocardial infarction (MORTAMIO),hemorrhagic stroke (MORTHSTO) and ischemic stroke (MORTISTO) were collected as a part of ongoing project by OECD.org in panels of 26 OECD countries over 2005-2015 period.Method: Panel data analysis.Results: There were committed relationships from nurse-staffing level to the enhancement of HCQI i.e.1％ increase in nurse-staffing level would reduce the rates of patient mortality based on MORTAMIO,MORTHSTO and MORTISTO by 0.65％,0.60％ and 0.80％,respectively.Furthermore,the role of nursestaffing level in increasing overall HCQI were simulated at the highest level in Sweden (-3.53),Denmark (-3.31),Canada (-2.59),Netherlands (-2.33),Finland (-2.09),Switzerland (-1.72),Australia (-1.64) and United States (-1.53).Conclusion: A higher proportion of nurses-staffing level is associated with higher quality of acute care services in OECD countries.Also,the nursing characteristics of Sweden,Denmark,Canada,Netherlands,Finland,Switzerland,Australia and United States would be good patts for other countries to maximize nursing outcomes in the care of patients with acute and life-threatening conditions by reducing the risk of complication,mortality and adverse clinical outcomes.