background. to describe a dermatitis outbreak caused by exposure to pine processionary caterpillar (thaumetopoea pityocampa) that took place on march 15th, 2006, in schoolchildren during their stay at a rural farm holiday centre in villahermosa del río (castellón). methods. a cross sectional epidemiological study was carried out on seventy schoolchildren, average age 10 years, and 3 teachers from castellón. a specific questionnaire was used to be filled in by the schoolchildren. results. six cases of dermatitis (attack rate 8.6%: 6/70) took place after children had swum in the heated farm pool and dried themselves with towels that had been left outside the heated pool enclosure, where they had come into contact with thaumetopoea pityocampa. the cases needed medical attention, with prescription of antihistamine drugs, corticosteroids, and cold showers. the risk of dermatitis from contact with thaumetopoea pityocampa was very high (odds ratio=157.2 confidence interval 95% 18.4-∞). thaumetopoea pityocampa were collected near the swimming pool and thaumetopoea pityocampa nests were observed on nearby pines. conclusions. the presence of thaumetopoea pityocampa near rural centres can cause outbreaks. health education for schoolchildren and the removal of thaumetopoea pityocampa nests near these centres are required.