A series of 2-(p-substituted benzylidene)-3-(5-ethyl-1, 3, 4-thiadiazol-2-yl) thiazolidin-4-ones were synthesized by the reaction of Schiff’s bases of N-(p-substituted benzylidene)-5-ethyl-1, 3, 4-thiadiazole-2-amines with thioglycolic acid in 1, 4-dioxane as solvent and studied for their in vitro antibacterial activity. Reaction of thiosemicarbazide with propanoic acid in presence of concentrated sulphuric acid led to the formation of 5-ethyl 1, 3, 4-thiadiazole-2- amines which on further reaction with different p-substituted benzaldehydes yielded the compounds Schiff’s bases of N-(p-substituted benzylidene)-5-ethyl-1,3, 4-thiadiazole-2-amines which is further reaction with thioglycollic acid in presence of small amount of zinc chloride in 1,4 dioxane as solvent gave title compounds These compounds were characterized by spectral analysis. All the synthesized compounds were evaluated for their in vitro for their antibacterial activity against two Gram positive bacterial strains (Bacillus subtilis and Staphylococcus aureus) and two Gram negative bacterial strains (Escherichia coli and Pseudomonas aeruginosa) and their minimum inhibitory concentration (MIC) were determined.