Summary Background Despite the importance of ST-segment elevation myocardial infarction (STEMI) in China, no nationally representative studies have characterised the clinical profiles, management, and outcomes of this cardiac event during the past decade. We aimed to assess trends in characteristics, treatment, and outcomes for patients with STEMI in China between 2001 and 2011. Methods In a retrospective analysis of hospital records, we used a two-stage random sampling design to create a nationally representative sample of patients in China admitted to hospital for STEMI in 3 years (2001, 2006, and 2011). In the first stage, we used a simple random-sampling procedure stratified by economic-geographical region to generate a list of participating hospitals. In the second stage we obtained case data for rates of STEMI, treatments, and baseline characteristics from patients attending each sampled hospital with a systematic sampling approach. We weighted our findings to estimate nationally representative rates and assess changes from 2001 to 2011. This study is registered with ClinicalTrials.gov, number NCT01624883. Findings We sampled 175 hospitals (162 participated in the study) and 18 631 acute myocardial infarction admissions, of which 13 815 were STEMI admissions. 12 264 patients were included in analysis of treatments, procedures, and tests, and 11 986 were included in analysis of in-hospital outcomes. Between 2001 and 2011, estimated national rates of hospital admission for STEMI per 100 000 people increased (from 3·5 in 2001, to 7·9 in 2006, to 15·4 in 2011; ptrend<0·0001) and the prevalence of risk factors - including smoking, hypertension, diabetes, and dyslipidaemia - increased. We noted significant increases in use of aspirin within 24 h (79·7% [95% CI 77·9-81·5] in 2001 vs 91·2% [90·5-91·8] in 2011, ptrend<0·0001) and clopidogrel (1·5% [95% CI 1·0-2·1] in 2001 vs 82·1% [81·1-83·0] in 2011, ptrend<0·0001) in patients without documented contraindications. Despite an increase in the use of primary percutaneous coronary intervention (10·6% [95% CI 8·6-12·6] in 2001 vs 28·1% [26·6-29·7] in 2011, ptrend<0·0001), the proportion of patients who did not receive reperfusion did not significantly change (45·3% [95% CI 42·1-48·5] in 2001 vs 44·8% [43·1-46·5] in 2011, ptrend=0·69). The median length of hospital stay decreased from 12 days (IQR 7-18) in 2001 to 10 days (6-14) in 2011 (ptrend<0·0001). Adjusted in-hospital mortality did not significantly change between 2001 and 2011 (odds ratio 0·82, 95% CI 0·62-1·10, ptrend=0·07). Interpretation During the past decade in China, hospital admissions for STEMI have risen; in these patients, comorbidities and the intensity of testing and treatment have increased. Quality of care has improved for some treatments, but important gaps persist and in-hospital mortality has not decreased. National efforts are needed to improve the care and outcomes for patients with STEMI in China. Funding National Health and Family Planning Commission of China. © 2015 Elsevier Ltd.