AbstractThe antimicrobial activity of a series of nitro‐heterocyclic drugs was determined and correlated with a number of physicochemical properties. The best correlation is found with the polarographic half‐wave potential, while the partition coefficient and LUMO‐values contribute poorly to the relationship. The value of the dipole moments can be used to discriminate between active 2‐nitro and 5‐nitroimidazoles and inactive 4‐nitroimidazoles. Free‐Wilson analysis emphasizes the need of structural parameters like the presence of the nitro group in position 2 or 5 or a methyl substituent on the imidazole ring. The activity is enhanced by a vinyl group in position 2 and is decreased by the presence of a pheny