A histochemical study using lectin methods was performed on myxosporean parasites from vastly different fish hosts from marine and fresh waters. Six biotinylated lectins were used (WGA, SBA, BS-I, Con-A, UEA-I and SNA). The binding pattern of Con-A and WGA revealed the presence of mannose and/or glucose, and N-acetyl-D-glucosamine respectively, in polar capsules and valves of most of the myxosporea assayed. Thus, chitin may be present in polar capsules and/or valves of myxosporean spores. The BS-I binding pattern showed the presence of alpha-D-galactose and/or N-acetyl-D-galactosamine residues in polar capsules of Kudoa sp., Zschokkella mugilis Sitjà-Bobadilla et Alvarez-Pellitero, 1993 and Leptotheca sp., and in the valves of the latter. Scarce amounts of N-acetyl-D-galactosamine and/or alpha-D-galactose were demonstrated by SBA binding in Sphaerospora dicentrarchi Sitjà-Bobadilla et Alvarez-Pellitero 1992, Leptotheca sp. and Kudoa sp. valves, and in Leptotheca sp. polar capsules. The UEA-I staining indicated the absence of alpha-L-fucose in all the myxosporea assayed except in Leptotheca sp. N-acetylneuraminic acid was detected with SNA in the polar capsules and sporoplasms of Polysporoplasma sparis Sitjà-Bobadilla et Alvarez-Pellitero, 1995 and in the polar capsules and valves of Kudoa sp. These results indicate that, although Myxosporea may have conserved carbohydrate structures, some of them can show significantly different binding patterns, which may be useful in diagnostic and functional studies.