Aspergillus carbonarius was recorded as a good producer of microbial cell wall lytic enzymes. The enzyme preparation effectively lysed both living and heat-treated cells of some bacteria and yeasts. Polymers of microbial cell wall constitution had been also hydrolysed. Production of the highest content of lytic enzymes was induced by killed cells of Escherichia coli. The crude preparation revealed its maximal bacteriolytic activity at pH 7.2 and 35 degrees C. Endo-1,3-beta--glucanase, mannanase and protease were the prevailing enzymes in this preparation.