ObjectiveThe objective is to determine the incidence of sudden unexplained death in childhood (SUDC) for children aged 1–14 years in England and Wales during 2001–2020.DesignObservational study using official national statistics on death registrations and child population.SettingEngland and Wales.PatientsChildren dying of SUDC, aged 1–14 years, registered as International Classification of Disease version 10 codes R95–99.Main outcome measuresIncidence of SUDC, proportion of child mortality due to SUDC.ResultsA total of 582 children aged 1–14 years died of SUDC, 450 (77.3%) deaths were in children aged 1–4 years, 55 (9.5%) in those aged 5–9 years and 77 (13.2%) in those aged 10–14 years. The number of SUDC was relatively stable with a mean of 29 cases per year (range 21–38, SD 4.2). Overall child mortality fell from 1482 deaths in 2001 to 826 in 2020. The incidence of SUDC for children aged 1–14 years ranged between 0.002 and 0.004 per 1000. The relative proportion of child mortality due to SUDC increased from 1.96% of all child deaths in 2001 to 3.03% in 2020 (p=0.103), SUDC accounted for 5.8% of deaths of children aged 1–4 years by 2020. At all ages, SUDC was more common in male children than female children.ConclusionThe incidence of SUDC has remained static despite overall child mortality almost halving in the last two decades. SUDC is now more widely recognised due to improved investigation, but there has been limited research into SUDC; potential causes and associated risk factors remain unknown. As the relative proportion of child deaths due to SUDC increases, child health professionals must be aware of SUDC to support bereaved families.