Many workers who used coal tar containing paints in shipyard industry have dermatitis, but the etiology is not known well. Our research is to fond out the etiology of the dermatitis and to provide proper management. Methods of this research are comprised of 3 steps. First, we diagnosed dermatitis by questionnaire and dermatologic examination and evaluated air level of coal tar pitch volatiles in workplace. Second, we confirmed coal tar phototoxicity by in vitro cell experiments. Third, we evaluated the effects of intervention. The results were as follows ; Questionnaire survey showed that the lesions of dermatitis were mainly on the sun exposed area and the symptoms were strongly associated with season, weather, and time. Air levels of coal tar pitch volatiles in workplace were higher than NIOSH standard (0.1 mg/m(3), cyclohexane solubles). Inhibitory effects of cellular proliferation by coal tar containing paints and UVA (365nm) exposure showed coal tar phototoxicity. Intervention was done by UV barrier cream(BPF 30) and 72.7% workers who applied UV barrier cream improved after 2 months later. Conclusively, the etiology of dermatitis of shipyard workers who used coal tar containing paint was coal tar phototoxicity, and this dermatitis would be protected by UV barrier cream.