A bacterium that produces L-fucose dehydrogenase [EC 1.1.1.122] constitutively was isolated from soil, and identified as Agrobacterium tumefaciens K-28. The enzyme, which was extracted from cells grown in a medium containing 1% sucrose as a sole carbon source, was purified about 150-fold with a 51.6% yield, and was found to be homogeneous on polyacrylamide gel electrophoresis (PAGE). The molecular weight of the purified enzyme was about 100,000 and the pl was about 4.4. The optimum pH was at 9.0 to 10.0, with pH stability from 7.5 to 9.0.