Abstract Background Infertility is a disease defined by failure to achieve a pregnancy within 12 months of trying. Infertility has-until now-not been monitored in Denmark for three decades. The aim of this study was to assess the prevalence of infertility in persons aged 25-44 years in the Capital Region of Denmark, and to describe characteristics of persons with infertility. Methods Life-long experience of infertility was assessed in the Danish Capital Region Health Survey 2021, including 56,245 participants from the general population aged ≥16 years (response rate 54.9%). In this study, only persons aged 25-44 years who had tried to have children (thus knowing their fertility) were included, resulting in 8,203 participants. Characteristics of persons with infertility were assessed using national registries (socio-demographics) and questionnaire data (health status). Descriptive analyses and multivariate logistic regression models weighted for survey design and non-response were performed. Results Among persons aged 25-44 years, who had tried to have children, 20% had experienced infertility. Among those, 44% did not achieve the children they wanted. Infertility was most common among women (22%) and persons aged 35-44 years (21%). No associations were observed between infertility and ethnicity, education, and employment status. Persons with infertility were more likely to have poor physical health, have higher level of stress symptoms and have obesity compared with persons in same age group, who had tried to have children but not experienced infertility. Conclusions Infertility is very common in the general population and is associated with unmet fertility desires as well as poor physical health and high stress level. These findings highlight the importance of focusing on and prioritizing treatment and prevention of infertility and emphasize the need for further research in and continued monitoring of infertility. Key messages • Infertility is very common in the general population and associated with unmet fertility desires and poor health highlighting the importance of prioritizing treatment and prevention of infertility. • Continuous monitoring of infertility in the general population is essential as well as further research into risk factors and consequences of infertility.