Background According to the regulations of the Chinese and Shanghai governments, migrant workers employed in Shanghai should all be entitled to Shanghai Migrant Worker Hospitalization Insurance (SMWHI) without premium and the vast majority should also have the New Rural Cooperative Medical System (NRCMS). This study aimed to examine the status of the coverage and utilization of health insurance among migrant workers employed in Shanghai.Methods Quantitative and qualitative research methods were employed in the study. A survey of 1020 migrant workers employed in Shanghai was conducted in 2010 with a structured questionnaire. Focus group discussions were held with respondents who were unable to maintain health insurance coverage through NRCMS or SMWHI. In-depth interviews were held with village heads and employers of the migrant workers, migrant workers who were hospitalized within the last year, and various individuals employed by the insurance agencies.Results The study found that 72.9% and 36.5% of migrant workers were covered by NRCMS or SMWHI, respectively,while 16.7% of them had no health insurance. The coverage by NRCMS among migrant workers correlated significantly with education level and workplace, while the coverage by SMWHI correlated significantly with the length of employment in Shanghai and workplace. The qualitative results confirmed that migrant workers were the main group who were not covered by NRCMS, and the coverage by SMWHI was completely dependent upon the employers of the migrant worker.The results also showed that health insurance utilization among migrant workers was strongly limited by hospital location.Conclusions We observed that the status of health insurance among migrant workers was not accordant with theory,and that Chinese health insurance policy should be further reformed in order to realize full coverage and equal utilization of health insurance among migrant workers in China.