Background and purpose — The choice between invasive and non-invasive treatment of diaphyseal forearm fractures in children can be difficult. We investigated the trends in choice of treatment of pediatric diaphyseal forearm fractures over a 20-year period. Patients and methods — This is a population-based register study with data from 1997 to 2016 retrieved from the Danish National Patient Registry. The primary outcome was choice of primary treatment within 1 week divided into non-invasive treatment (casting only or closed reduction including casting) and invasive (Kirshner wires, intramed-ullary nailing [IMN], and open reduction internal fixation [ORIF]). The secondary outcomes were further sub-analyses on invasive treatment and age groups. Results — 36,244 diaphyseal forearm fractures were investigated, yielding a mean incidence of 172 per 10⁵/year. The proportion of fractures treated invasively increased from 1997 to 2016, from 4% to 23%. The use of Kirschner wires increased from 1% to 9%, IMN increased from 1% to 14%, and ORIF decreased from 2% to 1%. The changes were evi-dent in all age groups but smaller in the 0–3-year age group. Conclusion — We found an increase in invasive treatment of pediatric diaphyseal forearm fractures over the investigated period. A change in invasive methods was also found, as the rate of IMN increased over the investigated period and became the predominant surgical treatment choice.