Cyano derivatives of 6-acyl-2(3H)-benzoxazolones were reacted with cysteamine HCl in ethanol to give the corresponding 6-acyl-3-thiazolinoethyl-2(3H)-benzoxazolones and their antibacterial and antifungal activities were investigated. The chemical structures were proved by means of their IR and H-1-NMR spectra and elemental analysis. Investigation of antimicrobial activity of the compounds was carried out by tube dilution and disc techniques using bacteria (Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853 and Streptococcus faecalis ATCC 29212) and yeast-like fungi (Candida parapsilosis, C albicans, C pseudotropicalis and C stellatoidea). Inhibitory effects were observed for many compounds against S aureus and Bacillus subtilis. Compounds 13 and 15 had minimum inhibitory concentrations (MIG) of 8.4 and 4.2 mu g/mL respectively. The antifungal studies against C albicans (10 and 16, MIC = 67.5 mu g/mL), C parapsilosis (15, MIC = 67.5 mu g/mL) and C stellaatoidea (9, MIC = 67.5 mu g/mL) were more successful in comparison.