Aim. Acinetobacter baumannii is a Gram-negative opportunistic pathogen responsible for a wide spectrum of hospitalacquired infections. This bacterium has acquired resistance to nearly all existing antibiotics, including aminoglycosides, quinolones, broad-spectrum β-lactams, carbopenems, polymyxins and even colistin which is a last-line antimicrobial agent, providing the stimulus to search for novel antibiotics. The aim of this study is to identify novel anti- Acinetobacter baumannii agents among 4H-chromen-4-one derivatives. Methods. 88 4H-chromen-4-one derivatives were tested by broth microdilution against five bacterial pathogens such as Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia, Acinetobacter baumannii, Pseudomonas aeruginosa and toward two fungal pathogens such as Candida albicans and Cryptococcus neoformans. Results. Among the derivatives we have found two active compounds — 6-Chloro-4-oxo-4H-chromene-3-carbonitrile (1) inhibiting growth of C. albicans (MIC = 0.5 mg/L) and C. neoformans (MIC = 0.25 mg/L) and 6-Chloro-3-(6-hydroxy-3-oxo-3H-benzofuran-2-ylidenemethyl)-chromen- 4-one (2), inhibiting growth of C. neoformans (MIC = 16 mg/L). In addition, compounds 1 and 2, at a concentration of 32 mg/L, inhibited the growth of A. baumannii ATCC 19606 by 24.8% and 23.7%, correspondingly. Compound 1 was revealed to inhibit the growth of multidrug resistant clinical isolate A. baumannii №144 with MIC value of 32 mg/L. Also, it was established that this compound is not cytotoxic toward HEK293 cells. Conclusions. Therefore, 6-Chloro- 4-oxo-4H-chromene-3-carbonitrile can be promising candidate for further research and chemical optimization.