We studied the safety of a trivalent inactivated surface antigen (split virion, inactivated) influenza vaccine, Begrivac® (Novartis Company), widely used in health care workers in Kurdistan. A longitudinal follow-up study was performed in Sanandaj city, west of Iran, recruiting 936 people. A questionnaire was completed for each participant, and all symptoms or abnormal physical findings were recorded. In part 1 of the study, the post-vaccination complaints were headache (5.3%), fever (7.9%), weakness (9.6%), chills (10.1%), sweating (10.5%), arthralgia (20.2%), and malaise (21.5%). Swelling of the injection site was seen in 267 (30.3%) participants, and pruritus of the injection site was seen in 290 (32.9%) participants. Redness and induration were also reported in 42.5% of the participants. Local reactions were mainly mild and lasted for 1-2 days. No systemic reactions were reported in the second part of the study. None of the participants experienced any inconvenience. We concluded that local adverse reactions after the trivalent inactivated split influenza vaccine, Begrivac®, in health care workers were far more common than expected. Continuous surveillance is needed to assess the potential risks and benefits of newly produced influenza vaccines.