New 2-, 4- and 5-nitroimidazole analogues were synthesised using the following methods: (i) SRN1 free radical reaction between nitroimidazole anion and halonitro substrates; (ii) oxidative addition of the anion of 2-nitropropane to nitroimidazole anions. N-1-alkyl derivatives of imidazole, benzimidazole, 5-nitrobenzimidazole, 5- and 6-nitroindazole were similarly prepared. These compounds showed antimicrobial activity; anaerobes were more sensitive than aerobes.