Mechanised production of peat for fuel consumption is associated with high concentrations of organic dust, which is inhaled by the peat workers. In the present study 17 workers at two peat bogs in northern Sweden were examined. Personal sampling of total dust and the respirable fraction was performed during several workshifts. Dynamic spirometry was carried out before and at the end of shifts. Bronchoscopy with bronchoalveolar lavage (BAL) was performed in six subjects at the end of the working season and the results were compared with unexposed reference subjects. Peat workers using modern machines with ventilated cabins containing air filters were found to be exposed to low concentrations of peat dust. The recorded dust concentrations were below the threshold limit value for organic dust (5 mg/m3 air) in all but one worker. The respirable fraction of peat dust recorded in the breathing zone of the workers correlated significantly with a decrease in forced expiratory volume in one second (FEV1). The effect on lung function in non-asthmatic peat workers was, however, small. The concentration of lysozyme positive alveolar macrophages in BAL fluid was significantly lower in the peat workers compared with reference subjects. An inverse correlation was found between the mentioned cells and exposure to the respirable fraction of the peat dust. Furthermore, one particularly dust exposed worker had pronounced increases in alveolar macrophages, fibronectin concentration, and mast cells in BAL fluid.