Supracondylar humerus fractures are usual in children but their recent trends are unclear. A population-based study was performed to determine the epidemiology of childhood supracondylar humerus fractures during the decade, 2000 to 2009, in a geographic area of Oulu, Finland. Altogether, 565 extension-type supracondylar humerus fractures were included. The fractures and their treatment were analyzed according to the Gartland classification. Fracture incidence increased by 28%, from 50.9 to 65.2 per 100,000 during 2000 to 2009 (β = 1.03, < 0.001). The increase was from 41.3 to 57.6 per 100,000 in girls (β = 1.9, < 0.001). Trampoline-related fractures in particular increased in girls. Type II fractures increased twofold from 7.1 to 16.3 per 100,000 (β = 1.1, < 0.001), whereas type I fractures decreased from 22.4 to 20.9 per 100,000 (β = -0.3, = 0.026).Surgical treatment increased during the 10 years study period from 32.6 to 51.8% ( = 0.022); it was in particular due to increase of operative care of type II fractures (from 5.9% in 2000-2001 to 37.1% in 2008-2009; = 0.011). Lateral pin fixation increased from nil to six (10.7%) ( < 0.001). The incidence and surgical stabilization of type II fractures in particular are increasing. There is a trend toward lateral pin fixation.