This study reports a record-high pertussis (whooping cough) epidemic in Denmark from August 2023 to February 2024. The highest incidence was observed in adolescents, while the peak incidence in infants was lower compared to previous epidemics in 2019 and 2016. Among infants aged 0–2 months, over half were hospitalized, and one infant died, highlighting the severity of the disease in the youngest age group. To protect infants, pertussis vaccination in pregnant women was introduced as a permanent part of the national vaccination program in January 2024. Improved vaccination surveillance in pregnant women is also being implemented. The epidemic's peak incidence was 337 cases per 100,000 population in November 2023, with a decline in January and February 2024. The study emphasizes the importance of timely childhood vaccinations and the need for continued efforts to ensure high vaccination coverage, particularly among pregnant women.This study reports a record-high pertussis (whooping cough) epidemic in Denmark from August 2023 to February 2024. The highest incidence was observed in adolescents, while the peak incidence in infants was lower compared to previous epidemics in 2019 and 2016. Among infants aged 0–2 months, over half were hospitalized, and one infant died, highlighting the severity of the disease in the youngest age group. To protect infants, pertussis vaccination in pregnant women was introduced as a permanent part of the national vaccination program in January 2024. Improved vaccination surveillance in pregnant women is also being implemented. The epidemic's peak incidence was 337 cases per 100,000 population in November 2023, with a decline in January and February 2024. The study emphasizes the importance of timely childhood vaccinations and the need for continued efforts to ensure high vaccination coverage, particularly among pregnant women.