We studied paediatric patients with human adenovirus (HAdV) infection during the 2011 outbreak in northern Taiwan to define the clinical features of different HAdV genotypes in children. Between January and December 2011, 637 patients <19 years of age exhibited culture-confirmed adenoviral infection in Chang Gung Memorial Hospital, and provided specimens available for genotyping by multiplex real-time PCR. Clinical data were collected retrospectively. Excluding five cases with multiple genotypes, 632 cases were included for analysis. Three genotypes were identified, including HAdV-3 (429/632; 67.6%), HAdV-7 (144/632; 22.6%) and HAdV-2 (59/632; 9.8%). Median age was 4.58 years (range 2 months to 18 years), with children infected with HAdV-3 significantly older (82.9% >3 years; p <0.001). Of the 621 inpatients, 98.2% had fevers and all exhibited respiratory symptoms, 75 patients (12.1%) had lower respiratory tract infections, 20 (3.2%) required intensive care (HAdV-2: 1; HAdV-3: 8; and HAdV-7: 11), and three died (all HAdV-7-infected). HAdV-3-infected patients were significantly more likely to have upper respiratory symptoms and a high serum C-reactive protein level >100 mg/L, whereas leucocytosis (white blood cell count >15 000/mm3) was more common in HAdV-2-infected patients (p 0.007). HAdV-7 infections were significantly associated with a longer duration of fever, leucopenia (white blood cell count <5000/mm3), thrombocytopenia (platelet count <150 000/mm3), lower respiratory tract infections, a longer length of hospital stay, and requiring intensive care (all p <0.001). Childhood HAdV-2, HAdV-3 and HAdV-7 infections may exhibit different clinical manifestations. Although HAdV-3 was the most prevalent genotype observed during the 2011 Taiwan outbreak, HAdV-7 caused more severe disease characteristics and outcomes.