The cell growth, production of exopolymers, and the molar ratio of glucose to mannose in the water-soluble non curdlan type exopolymer-B (WSNCE-B), which is one of three exopolymers purified from the culture of Agrobacterium sp., varied with carbon source, culture medium, and initial medium pH. The molar percentage of rhamnose, a minor component in WSNCE-B, varied up to 13%, dependent on physiological conditions. No rhamnose was found in the WSNCE-B purified from the culture with initial medium pH greater than or equal to 6.8. The relative amount of mannose in WSNCE-B increased regularly with the amount of yeast extract added to the mineral salts medium. The relative amounts of glucose, mannose, and rhamnose in the WSNCE-B can be controlled by varying culture conditions.