Objective To investigate safety of influenza A H1N1 vaccine vaccinations. Methods A total of 3 300 medical workers were vaccinated by batch of 200909012 influenza A H1N1 vaccine produced by Shanghai Biological Products Corporation Limited according to the principle of voluntary and concentration. The adverse reactions were observed within half an hour, three days and a week after vaccinations, respectively. Results The inoculators with local or systemic reaction reached 1.18% (39/3 300). There were 0.15% (5/3 300) of the inoculators with adverse reaction within half an hour; 0.70% (23/3 300) within 1 to 3 days after vaccination; and 0.33% (11/3 300) within 3 days to 1 week after vaccination. No severe adverse events were found. Conclusion Influenza A H1N1 vaccine vaccinations is an economic and effective way of influenza A H1N1 prevention with mild reactions.