N.sup.1 -Acetyl-N.sup.1 -(4-pyrimidinyl)-sulphanilamides substituted by a cyclopropyl group in 2-, 5- or 6-position, which are antibacterial agents against gram-positive bacteria such as staphylococci, streptococci, pneumonococci and against gram-negative bacteria such as salmonella, oscherichia and klebsiella strains; pharmaceutical compositions containing the aforesaid pyrimidines as antibacterial ingredients, and a method of treating diseases caused by such bacteria, by administration of such pyrimidines or pharmaceutical compositions containing them. 6 Claims, No Drawings
