Airborne endotoxin concentrations and the number of viable airborne gram-negative bacteria were measured in cow and calf stables. The total amount of airborne endotoxin varied between 36 and 761 EU m(-3) (EU endotoxin units) in tile cow stables, and between 44 and 262 EU m(-3) in the calf stables. No correlation was found between concentrations of airborne endotoxin and the number of viable airborne gram-negative bacteria.