OBJECTIVE To evaluate the safety and epidemiological effects on the first mass vaccination program, using the China-made A (H1N1) influenza vaccine. METHODS Descriptive epidemiology and cohort study design were used to assess the influenza A H1N1 vaccine on its safety and epidemiological effects. RESULTS 95 244 subjects were immunized with A (H1N1) influenza vaccine. 193 adverse events were reported through AEFI Management System, with the Reported rates of AEFI as 2.03‰. Most of the adverse events (137/193, 71.0%) happened during the first 24 hours after immunization was carried out. Of 81 adverse reactions confirmed to be related to immunization, with 78 (96.3%) showed mild reactions. No Guillain-Barre Syndrome related to vaccination was reported through the AEFI Management System. The epidemiological protection rate of A (H1N1) vaccine could reach 80.9% when the coverage was not considered. CONCLUSION The A (H1N1) influenza vaccine showed a similar safety profile to seasonal flu vaccine. The vaccine demonstrated a good epidemiological effects against A (H1N1) influenza virus infection.