To compare the clinical and laboratory characteristics and disease severity between adults and children with dengue in Taiwan in 2002, we retrospectively studied 661 serologically confirmed dengue-infected patients (606 adults and 55 children) admitted between June and December 2002 to a single medical centre. The medical charts of the patients were reviewed for demographic, clinical, laboratory and imaging information. Compared with children, adult patients were found to have: higher incidences of arthralgia (P<0.001), myalgia (P=0.002), headache (P=0.028), abdominal pain (P=0.004) and upper gastrointestinal bleeding (P=0.013); lower platelet counts (P<0.001), prothrombin time (P=0.030) and serum albumin levels (P=0.037); a higher incidence of elevated alanine aminotransferase levels (P=0.001); and a higher prevalence of dengue haemorrhagic fever (DHF) (14.4% vs. 3.6%; P=0.026). The current data showed differences in clinical manifestations and laboratory characteristics between children and adults with dengue virus infection. Notably, a higher incidence of DHF was observed in adult patients compared with children in the 2002 dengue epidemic in Taiwan.