Comparison of values of destruction degree of microorganisms of different types (Micrococcus luteus, Pseudomonas fluorescens, Bacillus cereus, Sarcina lutea bacterias and Saccharomyces yeasts) under the simultaneous treatment of water by cavitation and gas is carried out. Has been determined the nature of the gas in which the cells were most actively destroyed by comparing the values of destruction degree. The greatest effectiveness of microorganisms destruction was achieved with the Ar/US-action, regardless of the type of microorganisms, their morphological characteristics and their initial amount per unit volume of water. Morphological features have an influence only on the duration of cavitation treatment of water.