Ochratoxin A (OTA) is a nephrotoxin frequently contaminating grains. OTAinhalation during grain handling may therefore represent a health risk to farmers, and was the subjectof this study. Airborne and settled grain dust was collected during grain work on 84 Norwegian farms.Climate and agricultural practices on each farm were registered. Penicillium spp., Aspergillus spp. andOTA in settled dust were measured. Settled dust contained median 4 microg OTA/kg dust (range 2-128),correlating with Penicillium spp. (median 40 cfu/mg; range 0-32000, rs =0.33; p < 0.01). Similar levelswere found across grain species, districts and agricultural practices. Penicillium levels, but not OTAlevels, were higher in storage than in threshing dust (p=0.003), and increased with storage time (rs=0.51, p < 0.001). Farmers were exposed to median 1 mg/m3 (range 0.2-15) dust during threshing and median7 mg/m3 (range 1-110) dust during storage work, equalling median 3.7 pg/m3 (range 0.6-200) and median40 pg/m3 (range 2-14000) OTA, respectively (p < 0.001). Agricultural practices could not predict OTA,Penicillium or Aspergillus contamination. Compared to oral intake of OTA, the inhalant exposure duringgrain work was low, although varying by more than 1,000-fold. However, the farmers may occasionally behighly exposed, particularly during handling of stored grain.