Composition of a suspension aerosol drug, gentasol for local application was developed. It contained gentamycin and prednisolon. The antimicrobial properties of the drug were studied in vitro. It was found that gentasol had a pronounced antimicrobiol effect and inhibited the growth of many microorganisms including cultures resistant to other antibiotics. The drug was active against Ps. aeruginosa and Proteus, which is an advantage of it as compared to other antibiotic aerosol drugs. The study showed that gentasol had self-sterilizing properties.