Several 1-(4-aryl-2-thiazolyl)-3-(2-thienyl)-5-aryl-2-pyrazoline derivatives were synthesized by reacting substituted 3-(2-thienyl)-5-aryl-lthiocarbarnoyl-2-pyrazolines with phenacyl bromides in ethanol. The structures of the synthesized compounds were confirmed by H-1 NMR, C-13 NMR, and EIMS spectral data. Their antimicrobial activities against Escherichia coli (NRPL B-3704), Staphylococcus aureus (NRLL B-767), Salmonella typhinturium (NRRL B-4420), Bacillus cereus (NRRL B-3711), Streptococcus faecalis (NRRL B-14617), Aeromonas hydrophila (Ankara Uni. Fac. of Veterinary), Candida albicans and Candida glabrata (isolates obtained from Osmangazi Uni. Fac. of Medicine) were investigated. A significant level of activity was observed. (c) 2006 Elsevier Masson SAS. All rights reserved.