Sixty strains of Fusarium oxysporum were characterized by (i) in vitro growth parameter estimates on four carbon sources and (ii) vegetative compatibility grouping. Growth was assessed by measuring optical density changes of fungal cultures in microtiter plates. Principal component analyses of growth parameters estimates permitted a good discrimination of the isolates on the four carbon sources and revealed a high level of diversity within populations of F. oxysporum. The 60 strains were assigned to 40 vegetative compatibility groups. Strains grouped in a given vegetative compatibility group had similar growth parameters. Trophic characterization and vegetative compatibility groups were compared to a genotypic characterization previously performed on this collection. Trophic characterization and vegetative compatibility grouping were more discriminating than the genotypic characterization. The three characterization methods suggested that vegetative compatibility groups could be considered the population unit among natural F. oxysporum populations.