ABSTRACT: Thiazolidin-4-one fused pyrimidines, [1,5]-benzodiazepines and their oxygen substituted hydroxylamine derivatives have been screened for antibacterial, antifungal and antimalarial activity. Bacillus subtilis, Escherichia coli, Proteus mirabilis and Salmonella typhi were used for antibacterial screening. Aspergillus fumigatus and Candida albicans were used for antifungal screening and Plasmodium species were used for antimalarial screening. The antibacterial and antifungal activities are expressed in terms of zone of inhibition and antimalarial activity is expressed in IC(50) value. Fifteen compounds 2Xa, 2Xb, 2Xc, 2Xs, 3IV, 3Va, 3Vc, 3VIIIa, 3VIIIh, 3IXa, 3IXb, 3IXc, 3Xa, 4IXa and 4Xa were tested for antibacterial as well as antifungal activity and seven compounds 2IXb, 2Xb, 3VIIIc, 3Xc, 4
