Herein we outline the antibacterial activity of amino acid containing thiazolidinediones and rhodanines against Gram-positive bacteria Staphylococcus aureus ATCC 31890, Staphylococcus epidermidis and Bacillus subtilis ATCC 6633. The rhodanine derivatives were generally more active than the analogous thiazolidinediones. Compounds of series 5 showed some selectivity for Bacillus subtilis ATCC 6633, the extent of which is enhanced by the inclusion of a non-polar amino acid at the 5-position of the core thiazolidinediones and rhodanines scaffolds. SAR data of series 8 demonstrated improved activity against the clinically more significant Staphylococci with selectivity over Bacillus subtilis ATCC 6633 induced by introduction of a bulky aryl substituent at the 5-position of the core scaffolds.