The background of this article is to examine whether consecutively transgender clinic-referred adolescents between 2000 and 2016 differ over time in demographic, psychological, diagnostic, and treatment characteristics. The sample under study consisted of 1072 adolescents (404 assigned males, 668 assigned females, mean age 14.6 years, and range 10.1–18.1 years). The data regarding the demographic, diagnostic, and treatment characteristics were collected from the adolescents’ files. Psychological functioning was measured by the Child Behaviour Check List and the Youth Self-Report, intensity of gender dysphoria by the Utrecht Gender Dysphoria Scale. Time trend analyses were performed with 2016 as reference year. Apart from a shift in sex ratio in favour of assigned females, no time trends were observed in demographics and intensity of dysphoria. It was found, however, that the psychological functioning improved somewhat over time (CBCL β − 0.396, p < 0.001, 95% CI − 0.553 to − 0.240, YSR β − 0.278, p < 0.001, 95% CI − 0.434 to − 0.122). The percentage of referrals diagnosed with gender dysphoria (mean 84.6%, range 75–97.4%) remained the same. The percentage of diagnosed adolescents that started with affirmative medical treatment (puberty suppression and/or gender-affirming hormones) did not change over time (mean 77.7%; range 53.8–94.9%). These findings suggest that the recently observed exponential increase in referrals might reflect that seeking help for gender dysphoria has become more common rather than that adolescents are referred to gender identity services with lower intensities of gender dysphoria or more psychological difficulties.