Naturally occurring tetraol lagochilin (1) belongs to the bicyclic diterpenoids with grindelic (9,13-epoxilabdanic) carbonic schelet [1]. Mentioned compound and some its derivatives were isolated from plants of Lagochilus genus which includes about 30 species widespread in Middle Asia [2, 3]. Plants of this genus and some pharmacological preparations based on them are used as strong hemostatics with sedative and anti-allegic affects [4]. This research was devoted to finding of new apllications for lagochilin (1) and a series of its synthetic derivatives which were prepared by known procedures. Their structure were proved using advanced NMR technics.formulaLagochilin (1) and some its derivatives were screened for their in vitro antifungal and antibacterial activity against pure cultures of five fungi species (Aspergillus flavus, A. niger, Penicillium frequentans, P. chrysogenum, Alternaria alternata) and against both Gram-negative (Pseudomonas aeruginosa) and Gram-positive bacteria (Bacillus polymyxa) [5]. According to these, lagochilin (1), 3,18-O-isopropyl lagohirsin (2) and 15,16anhydrolagochilin (3) exhibited good antimicrobial/antifungal activity at following MIC values (3.2·10-2/2 μg/mL), (1.6·10-2/2 μg/mL) and (2.3·10-2/3 μg/mL) in comparison with the reference compounds Caspafungin (16·10-2 μg/mL) and Kanamycin (2 μg/mL). It must be mentioned that antimicrobial and antifungal activities of lagochilin (1) and its derivatives were reported for the first time.