Evidence is limited on the association between hyperuricaemia and mortality in children and adolescents. This study was to investigate this association in the paediatric population. The study included children and adolescents who had undergone serum uric acid (SUA) measurement at the Chang Gung Memorial Hospital between 1997 and 2008. The survival status and cause of death of the included were ascertained by examining the National Death Registry of Taiwan. Hyperuricaemia was defined as a SUA level greater than 7.0 mg/dL. We included 13,241 patients (male, n = 7,454; female, n = 5,787) of mean age 14.3 ± 4.9 years. During the 82,800 person-years of follow-up, 455 deaths were identified, which corresponded to a crude mortality rate of 5.50 deaths per 1,000 person-years. Compared with individuals with a SUA <6.0 mg/dL, those with a SUA of 6.0-8.9, 9.0-11.9 and ≥12 mg/dL had an age- and sex-adjusted HR (95% CI) of 1.02 (0.82-1.26), 1.48 (1.08-2.02) and 4.73 (2.67-8.37). After adjustment for age, sex and history of diabetes mellitus and hypertension, hyperuricaemia was found to be associated with a HR (95% CI) of 1.38 (1.13-1.69; p < 0.001) for all-cause mortality. Hyperuricaemia was associated with an increased risk of mortality due to cardiovascular diseases (HR, 5.0; 95% CI 1.79-13.94; p = 0.001) and kidney diseases (11.71; 3.13-43.78; p < 0.001). Paediatric patients with hyperuricaemia were at increased risk of mortality, especially due to kidney and cardiovascular diseases.