An outbreak of dermatosis occurred in a livestock fodder factory at Kyongju in May 1994. Authors conducted a questionnaire survey on 60 workers in the factory and a dermatologist examined their skin lesion. Authors also collected mites and identified them. The obtained results were summarized as follows; 1. Twenty-eight cases of dermatosis were identified with attack rate of 46.7%. Attack rate was not different by department, age, sex, educational level and employment duration. Attack rate was 67.5% in productive worker and 5.0% in clerical workers (p<0.01) but was not significantly different between departments among productive workers (p>0.05). 2. Three cases among 28 dermatosis cases and one subject among 32 non-cases had a history of same dermatosis last year. Only one of dermatosis cases had a history of dermatosis among family members. History of other skin lesion and allergy was very rare in both cases and non-cases. 3. Skin lesions of the cases were rice-sized erythematous rapules or vesicles with a central biting point. Onset date of dermatosis was between May 1 and June 10. Duration was from one day to more than 30 days. Skin lesion was most frequent at the back(75.0%), and also observed at the arms(64.3%), abdomen(60.7%), legs(57.1%), chest(32.1%) and neck (25.0%). Skin lesion was aggravated while workers are sweeping the floor(35.7%), working at the workplace(21.4%) and in bed at night(28.6%). 4. Total 1,637 mites were collected and identified into 3 suborder, 7 families and 17 species. Dermatophagoides farinae was most frequent md most of the species identified were blood sucking mites. Authors concluded that the. outbreak of dermatosis was brought about by mite-bites and grain beetle parasitizing Acarophenax tribolii was the most suspected species. Further studies to identify the specific species causing dermatosis and route of import are needed.