To investigate treatment-seeking delays in Chinese patients with acute myocardial infarction (AMI) and to compare sex differences in this behaviour. A descriptive cross-sectional study was undertaken in patients with AMI, admitted to one of three hospitals in Shanghai, China. A treatment-seeking behaviour questionnaire was administered to each patient within 48 h of hospital admission. In total, 250 patients were included: 159 men and 91 women. The median time for patients with AMI to make a treatment-seeking decision was 130 min. Women took significantly longer to seek treatment than men (240 min versus 120 min). The majority of patients (70.8%) took >1 h to decide to seek treatment. The emergency medical service (EMS) was used by 77 (30.8%) of patients, and these patients had a significantly shorter prehospital delay time than those who transported themselves to hospital. Predictive factors for using the EMS were pain level and rating AMI symptoms as severe. Chinese patients with AMI had a significant prehospital delay time and women took longer than men to seek treatment. Public awareness of the importance of seeking immediate medical assistance for AMI via the EMS needs to be increased in China.