Hairy cell leukaemia (HCL) is a rare non-Hodgkin lymphoma of unknown aetiology most frequently diagnosed in males. In earlier epidemiological studies of HCL, exposures to benzene and chemicals appear to be risk factors. Since 1984, 48 patients (36 men and 12 women) with HCL has been treated in Uppsala. Information on occupation was collected from the medical records. 29 percent (13 men and one woman) worked in farming. One additional man worked in gardening. Of the men, 39 percent had this kind of work giving an OR of 7.5 (CI. 4.2-13.2) compared with the general Swedish population in 1970. A larger case control study is now being conducted.