Background A voluntary surveillance scheme of occupational skin diseases (OSDs) in The Netherlands starting in 2001 aimed to improve insight in the incidence of OSD especially occupational contact dermatitis (OCD), risk professions and causal agents. This paper presents the results of this scheme during 2001-05. Methods Reports of new cases of OSD received from the participating dermatologists on a monthly basis were analysed. Data evaluated included information on diagnosis, sex, age, sickness, absenteeism, profession and causal agents. Relative differences in incidence rates between industries or branches were estimated by calculating incidence rate ratios. Results About 80% of the notifications concerned OCD. The highest number of notifications was recorded in the first year of the scheme. This was probably due to reporting of a mixture of incident and prevalent cases. During the following 5 years, the number of yearly notifications of OSD declined. Hairdressers, nurses, metalworkers, mechanics and cleaners were the most commonly affected professions. Wet work and irritating substances were the most frequently reported causal agents. Most patients with OCD were not absent from work. Conclusions A voluntary surveillance scheme with dermatologists provides valuable data about the distribution of OCD in risk professions and the causal agents. However, it has certain limitations in assessing trends in incidence. Active medical surveillance in populations at risk should be encouraged not only to improve secondary prevention but also to obtain more reliable information about the incidence of OCD.