The number of patients presenting for care at gender clinics is increasing, yet the proportion of adults in the general population who want gender-affirming medical treatment remains essentially unknown. We measured the wish for cross-sex hormones or gender-affirming surgery, as well as other aspects of gender incongruence, among the general adult population of Stockholm County, Sweden. A population-representative sample of 50,157 Stockholm County residents ages 22 and older comprise the Stockholm Public Health Cohort. They were enrolled in 2002, 2006, and 2010 and followed-up in roughly 4-year intervals, with questions on health, lifestyle and social characteristics. In 2014, participants received the item "I would like hormones or surgery to be more like someone of a different sex." Two additional items concerned other aspects of gender incongruence: "I feel like someone of a different sex", and "I would like to live as or be treated as someone of a different sex." Each item had four answer options ("Not at all correct", "Somewhat or occasionally correct", "Quite correct", and "Absolutely correct"). For each item, any of the three affirmative answer choices were considered as some level of agreement. Calibration weights were used to estimate population-representative rates with 95% confidence intervals. The desire for cross-sex hormones or surgery was reported by 0.5% (95% CI, 0.4%-0.7%) of participants. Feeling like someone of a different sex was reported by 2.3% (95% CI, 2.1%-2.6%). Wanting to live as or be treated as a person of another sex was reported by 2.8% (95% CI, 2.4%-3.1%). These findings greatly exceed estimates of the number of patients receiving gender-affirming medical care. Clinicians must be prepared to recognize and care for patients experiencing discomfort due to gender incongruence and those who would like gender-affirming medical treatment.