Azotobacter vinelandii is a widely distributed free-living soil bacterium. This Gram-negative, strictly aerobic bacterium has many interesting features, including the ability to grow on a wide variety of carbohydrates, alcohols and organic acids, alginate production and nitrogen fixation. Sequence analysis of P. stutzeri genes that are specifically activated in the rice rhizosphere revealed high sequence similarity to A. vinelandii genes. These observations and the availability of a genome sequence of A. vinelandii and several Pseudomonas species urged us to inspect the phylogenetic relationship of A. vinelandii to Pseudomonas sensu stricto. Our in silico data strongly suggest that A. vinelandii belongs to the genus Pseudomonas sensu stricto.