Four strains (3, 5, 8, and 18) of Bipolaris sorokiniana were assessed as to their antigenic and partial. chemical composition through antisera produced in rabbits. The antisera were immunochemically analyzed by double diffusion and immunoelectrophoresis. The partial chemical characterization of exoantigens was obtained by measuring the amount of proteins, carbohydrates and lipids in the strains. Immunoelectrophoresis showed that strain 18 antigens stimulated the production of nine precipitin bands. No significant differences were found between the antisera produced by the animals immunized with the same antigen. Partial chemical analysis showed protein content between 173.4 and 332.2 mu g mL(-1); carbohydrate levels between 0 and 64.3 mu g mL(-1); and lipid content from 0 to 166 mu g mL(-1). Immunodiffusion and immunoelectrophoresis associated with chemical characterization are relevant when phenotypic traits of different strains of the same fungus species are studied. (c) 2004 Elsevier Ltd. All rights reserved.