Background. Hairdressers are at risk of developing occupational contact dermatitis because of their intense contact with wet work in combination with chemicals. Objectives. To perform an analysis of a cohort study of hairdressers with occupational contact dermatitis recognized in the period 2006-2011, focusing on individual and environmental factors associated with the disease. Methods. The study was a descriptive, register-based survey including all hairdressers with recognized occupational contact dermatitis in Denmark in the period January 2006 to September 2011. Data were obtained from the Danish National Board of Industrial Injuries. Results. The study comprised 381 patients (373 women and 8 men). The median age was 25 years, 64.8% were apprentices, and 35.2% were fully trained hairdressers. The prevalence of atopic dermatitis was 36.0%, and was significantly higher among apprentices than among fully trained hairdressers (44.9% and 19.4%, respectively) (p< 0.001). Of the patients, 48.3% had their dermatitis recognized as occupational irritant contact dermatitis, 46.7% had their dermatitis recognized as as occupational allergic contact dermatitis or combined allergic and irritant contact dermatitis, and 5.0% were recognized as having occupational contact urticaria. Conclusion. The low median age, the high percentages of atopic dermatitis in apprentices and the fact that more apprentices than fully trained hairdressers had recognized occupational contact dermatitis underlines the importance of early prevention.