N.sup.1 -(1,2-dihydro-2-oxo-4-pyrimidinyl)sulfanilamides, bearing a lower alkyl, cycloalkyl or cycloalkyl-lower alkyl substituent in the 1-position, prepared by reaction of the corresponding 1-substituted-1,2-dihydro-2-oxo-4-aminopyrimidine and N-acylated sulfanilyl chloride with subsequent hydrolysis, are described. The end products are useful as antibacterial agents.