Dissertation (Msc. Chemistry)New series of four, (Z)-5-(4-chlorobenzylidine)-2-(Aryl/Substituted arylimino)thiazolidin-4-one and one (Z)-5-(4-chlorobenzylidine)-3-(2,5-dichlorophenyl)-2-iminothiazolidin-4-one were successfully synthesized from aryl/substituted aryl amines by employing nucleophilic substitution reaction with chloroacetyl chloride to form chloroacetamide. The formed acetamides were nucleophilically reacted with potassium thiocyanate coupled with Cyclization to form N-substituted thiazolidin-4-one ring followed by aldol condensation reaction with a p-chlorobenzaldehyde to form the targeted compounds. The structures of the new compounds were established by IR, MS, and 1H-NMR. The compounds were evaluated for antimicrobial activities by agar well diffusion method against Gram-positive bacteria: Staphylococcus aureus, Bacillus subtilis, Gram-negative bacteria: Salmonella typhi, Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa, and two fungi which were Aspergillus niger and Candida albicans. The MIC of the compounds was also determined by the serial dilution method. The compounds were also evaluated for toxicity by performing the brine shrimp lethality test (BST). All the synthesized compounds showed good to moderate antimicrobial activity on the antimicrobial susceptibility test whereby the compounds containing halogen groups in benzene ring that is bonded to nitrogen displayed good and significant antimicrobial activity compared to the standard drug. However, the MIC value and toxicity test showed that two compounds (S3-03 and S4-03) have good to moderate antimicrobial activity, both having MIC values ranging from 2.5 mg/mL to 343.3 mg/mL and LC50 of 123.941 μg/mL and 9500 μg/mL respectively while one compound (S2-03) expressed the potentiality of being new drug candidate for anticancer having MIC values ranging from 0.0025 mg/mL to 343.3 mg/mL with LC50 of 7.840 μg/mL.