Total aerobic bacteria and fluorescent pseudomoonads were counted in bulk and rhizospherie soils of banana plants of 14 plantations in Martinique (French West Indies). Fluorescent Pseudomonas isolates were then identified and investigated for in vitro antagonism towards Cylindrocladium sp., a fungal pathogen of banana roots. Total aerobic bacteria and fluorescent pseudomonads were significantly more abundant in rhizospheric soils than in bulk soils. Among 58 fluorescent Pseudomonas isolates, 41 were identified, as Pseudomonas fluorescens biovar V and 17 as Ps. Putida biovar A. Six strains exhibited an antagonism towards Cylindrocladium isolates. Among, them, Ps. Putida strain 93.1 totally blocked fungal growth. No relationship was established between the antifungal effect and enzymc or hydrogen cyanide production by bacteria, suggesting that siderophores and other compounds were involved in fungal inhibition. Antagonistic fluorescent pseudomonads represent a potential for the biological control of banana root infections by Cylindrocladium sp.