In the presented study we wanted to establish a biological monitoring of exposure in farmers occupationally exposed to phenoxy acid herbicides (MCPA, dichlorprop mecoprop, and 2,4-D). The individual airborn concentrations were measured as well as the urinary concentration before, during and after exposure. Twentyfour male farmers and nine professional spray-men were studied and compared. The air concentrations were low, less than 0.001-0.1 micrograms/m3. Urinary concentrations were variable less than 0.05-12 micrograms/ml (MCPA). Uptake by dermal absorption seems to be dominant, swallowing of sprayed droplets and inhalation are possible routes of entrance. Urinary concentrations of phenoxy acid herbicides (MCPA, dichlorprop, and mecoprop) measured at the end of an exposure period or preferably the following morning could be used to give a reflection of recent exposure.