To study the antimicrobial properties of 2-thioxo-4-thiazolidinone enaminone derivatives with a L-β-phenyl-α-alanine fragment in molecule. Methods. Diffusion in agar; serial dilutions in agar. Clinical isolates of microorganisms: methicillin-sensitive strain of Staphylococcus aureus (MSSA), methicillin-resistant strain of Staphylococcus aureus (MRSA), methicillinresistant strain of Staphylococcus haemolyticus (MRSH), Escherichia coli; Pseudomonas aeruginosa, ESβL + Klebsiella pneumonia, Candida albicans, Candida tropicalis. Results. Screening of antimicrobial activity of 13 new2-thioxo-4-thiazolidinone derivatives was carried out. The methicillin-resistant strain of Staphylococcus aureus (MRSA) was the most sensitive to the tested compounds. A number of derivatives exhibit synergism in combination with amoxicillin against the ESβL+ Klebsiella pneumonia strain. The structure-antimicrobial activity relationshipis was analyzed in detail. Conclusions. The tested 5-R-aminomethylene derivatives of ethyl 2-(4-oxo-2-thioxothiazolidin-3-yl)-3-phenylpropionic acid exhibit the