Acute promyelocytic leukaemia (APL) exhibits peculiar epidemiological, clinical, cytogenetic and molecular features, compared to the other acute myeloid leukaemias (AML). Data on epidemiology and occupational risk factors for APL desumed from the GIMEMA archive are reported and compared with those of the other AML. An exploratory case-case study was designed on AML patients from 56 haematology centres in Italy. Overall, 4296 patients older than 15 yr with a new diagnosis of acute leukaemia were recorded between July 1992 and July 1997. Of these, 335 were classified as APL, and 2894 as other AML. The median age of APL patients was 43 compared to 59 yr for the other AML (p < 0.00001). In order to identify peculiar risk factors for APL development, different parameters were compared in the 2 groups. After adjusting by age no significant differences were observed with regard to education, lifetime prevalence of cancer among siblings and previous diseases in the patient's history. Occupational exposure as a possible risk factor for APL showed no increased risk compared to other AML among farmers, builders and leather workers. A significant association was found in electricians (OR=4.4, 95% CI=2.0-9.7) and a weak association was found in wood workers (OR=3.2, 95% CI=0.8-10.8). The proportion of APL with respect to other AML was significantly higher in the north east of Italy compared to the rest of the country (OR=1.7, 95% CI=1.3-2.2). These data confirm the younger age of APL patients compared to the other AML. A possible role of electromagnetic fields is suggested by the higher risk of APL in electrical workers and in the more industrialized areas of the country.