Influenza vaccination is increasing with the concern of pandemic advance. Worldwide, two types of influenza vaccines are available; inactivated, trivalent, intramuscular vaccine (ITIV) is approved for use among children (≥6 months of age) and adults, while live attenuated intranasal vaccine (LAIV) is indicated for healthy persons 5 to 49 years of age. LAIV has not been used in Korea. In this review, the safety of ITIV is discussed with a particular attention to various subgroups at high risk. In general, local skin reactions are relatively frequent (10~65%), but these are usually self-limiting within 2 days after vaccination. Systemic adverse reactions are very rare compared to local reactions; fever, arthralgia, myalgia, and headache are noted with the incidence less than 15%. The risk of influenza vaccine-related Guillain-Barre syndrome is reported to be lower than that among non-recipients. As for the thimerosal (vaccine preservative), many people have worried about its neurotoxicity, but the benefits from influenza vaccination are considered to outweigh; single-syringe vaccine is recommended only for infants, pregnant women, and persons with thimerosal hypersensitivity. As in healthy persons, ITIV is proven safe in infants, pregnant women, elderly persons, immunocompromised patients, and patients with asthma. ITIV should be avoided in patients with egg allergy; instead, cell-cultured influenza vaccine or antiviral chemoprophylaxis would be recommended.