The influence of IPO-8831 insecticide on the respiration of soil microflora was estimated by determination of respiration modification indexes. Side effects of some of the formulation's components were high (phosalone, xylene), whereas the other ingredients (methoxychlor, deltamethrin, BHT) had only limited influence on the microorganisms population. A possible synergetic influence of the formulations components on the soil microflora respiration was also found.