7-[D(-)-α-(4-Alkyl-2, 3-dioxo-1-piperazinecarboxamido) phenylacetamido]-3-substituted methyl-3-cephem-4-carboxylic acids (I) were prepared. In vitro antibacterial activity against S. aureus, E. coli, Ps. aeruginosa, P. vulgaris and K. pneumoniae was tested and it was found to have a strong antibacterial activity against gram-negative bacilli, especially to Ps. aeruginosa and P. vulgaris.
