Evidence suggests the incidence of gender dysphoria (GD), a condition characterized by psychological distress caused by a mismatch between an individual’s gender identity and biological sex assigned as birth, has increased since the turn of the twenty-first century. We examined trends in the number of GD diagnoses and legal gender changes in Sweden using registry data from 5007 individuals diagnosed with GD between 2005 and 2017 (53.5% assigned female at birth). GD diagnoses increased substantially over time, especially in birth-assigned females and younger age groups. One-third of all subjects with GD legally changed their gender, with an increase of 1000% from 2005 to 2018. Generally, individuals who were assigned female at birth changed their gender earlier than birth-assigned males, and most did so within one year of GD diagnosis. Our findings highlight the need to analyze the causes and correlations of rapid changes in clinical presentation and to prepare healthcare systems for rising patient demand.