In previous studies 1-methyl-2-nitro-1H-imidazole-5-carboxaldehyde and 1-methyl-2-nitro-5-vinyl-1H-imidazole were found to posses interesting antimicrobial activities. We have now prepared some 2-nitro-1H-imidazoles in which the 5-vinyl chain bears selected functional groups (CHO, COCH3, NO2) as well as nitrogen-condensation derivatives of the carbonyl functions. Furthermore, 5-methyl-2-nitro-1-vinyl-1H-imidazole has been synthesized. All the compounds, and some intermediates, have been assayed for antimicrobial activity. Several of them exhibited significant antibacterial and antitrichomonal activity in mice.