Twenty-one new 1-methyl- and -disubstituted-4,5-dihydro-1H-1,2,4-triaz
ol-5-ones were synthesized and characterised by elemental analysis, H-
1-NMR and IR spectra. These new and 16 recently reported derivatives o
f 4,5-dihydro-1H-1,2,4-triazol-5-one ring were screened for their anti
bacterial activities.