This article explores seasonality, epidemiology and dominant epidemic strains of influenza in Taiwan. Surveillance in Taiwan demonstrates that influenza is a disease which occurs throughout the year but has peak activity in winter. Due to the high mutability of influenza virus, effective vaccination is the best strategy for protection. Although the World Health Organization-recommended vaccine compositions usually matched with around 77% of circulating strains worldwide, the rate of matching in Taiwan has been markedly lower than this. Between 1997 and 2004 in Taiwan, the match rates were 82% for H1N1, 53% for H3N2, and 47% for influenza B virus. Furthermore, some world epidemic strains appeared earlier in Taiwan than in other countries. In view of Taiwan's proximity to southern China, which is thought to be the epicenter of influenza epidemics, vigilant surveillance and the development of regional strategies for the selection and manufacture of vaccine strains to improve influenza prevention are urgent requirements.