Eight textile printing factories in Valencia, Spain, with a total workforce of 257 using spraying techniques were investigated as a result of severe interstitial lung disease occurring in three employees, one of whom died. Clinical and radiological data together with biopsy specimens from 71 (27.6%) workers with abnormal respiratory features indicated the occurrence of an outbreak of organising pneumonia resulting in 6 deaths. Epidemiological analysis included the 22 workers who fulfilled the radiological case definition based on chest radiograph and computed tomographic scan showing widespread nodular opacities or confluent patchy consolidation with a lung biopsy corresponding to organising pneumonia. The overall attack rate was 8.9%. Only 2 of the 22 cases never worked in factories A or B. Those who had only worked in factory A had the highest risk of being a case (RR = 24.3; 95% CI = 5.7-104.4). The relationship of case status to period of employment suggested an abrupt change in exposure conditions in the period when Acramin FWR was substituted by Acramin FWN. Although the precise toxicological mechanism is unknown, it is proposed that the lung disease was caused by spraying procedures delivered a respirable aerosol of Acramin FWN to distal airways and pulmonary parenchyma.