We have studied the possible in vitro and in vivo antibacterial activity of 5-fluoro-2-(5'-nitro-2'-furyl)benzimidazole (F-O-NO2). Our data demonstrate that F-O-NO2 is able to inhibit the in vitro growth of different mycetes and bacteria, including Candida albicans and Cryptococcus neoformans. We also tested the possible in vivo activity against Candida albicans. The results clearly show that treatment with F-O-NO2 is able to significantly augment the survival of all treated animals; in particular, when injected i.p. at the dose of 120 mg/kg, 30' or 1 hr after Candida albicans challenge, it givens a MST (Medium Survival Time) longer than 60 days. These data demonstrate that F-O-NO2 has antibacterial and antimycotic activity.