Background: Variations in care and outcomes by sex in patients with acute coronary syndrome (ACS) have been reported worldwide. The aims of this study are to describe ACS management according to sex in China and the effects of a quality improvement program in Chinese male and female ACS patients. Methods and results: Clinical Pathways for Acute Coronary Syndromes - Phase 2 (CPACS-2) was a cluster randomized trial to test whether a clinical pathways-based intervention would improve ACS management in China. The study enrolled 15,141 hospitalized patients [4631 (30.6%) werewomen] from 75 hospitals throughout China between October 2007 and August 2010. The intervention included clinical pathway implementation and performance measurement using standardized indicators with 6 monthly audit-feedback cycles. Eight key performance indicators reflecting in hospital management of ACS were measured. After adjustment for differences in patient characteristics and comorbidities at presentation, women were significantly less likely to undergo coronary angiography when indicated (RR 0.88 [0.85 to 0.92], P < 0.001), less likely to receive guideline recommendedmedical therapies at discharge (RR 0.94 [0.91 to 0.98], P = 0.003) and more likely to be hospitalized for shorter (mean difference -0.42 [-0.73 to -0.12] days, P = 0.007). However, in-hospital clinical outcomes did not differ by sex. There was no evidence of heterogeneity in the relative effects of the quality improvement initiative by sex. Conclusions: Sex disparities were apparent in some key quality of care indicators for patients with suspected with ACS presenting to hospitals in China. The beneficial effect of the quality improvement program was consistent in women and men. (C) 2017 Published by Elsevier Ireland Ltd.