The nitroimidazoles were launched on their pharmacological career in 1956 when azomycin or 2-nitroimidazole, a natural product obtained by fermentation, was found active against certain bacteria and Trichomonas, For a decade, nitroimidazole derivatives were used only to combat protozoa of the Trichomonadida order(1)(including Histomonas meleagridis in veterinary medicine), and for Vincent’s angina, a spirochaetal infection. Subsequently their use was extended to other parasitic infections (2), mainly amoebiasis and giardiasis, and only in the last five years have they been definitely employed in bacteriology (3) (Fig. 1) and as radiosensitizers.