A novel formulation of tebuconazole in microemulsion state was prepared in this work. The microemulsion was formed due to the presence of a special system of surfactants, namely ethoxylated castor oil and fatty acid amides. Biological effect of suspension concentrate and microemulsion formulations of tebuconazole with the same concentration of active ingredient was investigated in the field experiments. The experiments demonstrated excellent efficiency of the microemulsion containing 60 g/l of tebuconazole against broad spectrum of crop diseases and infections including smut diseases, root rots and moulds in comparison to suspension concentrate at the same application rate.