Tubulin was estimated to account for 16.3% and 0.25% of protein in rat brain and Nippostrongylus brasiliensis supernatants, respectively. Tubulin from N. brasiliensis and rat brain have been partially purified using polylysine agarose chromatography and high performance liquid chromatography on a gel permeation column. Western blots with alpha- and beta-tubulin monoclonal antibodies confirmed the presence of tubulin in different fractions. The mobility of N. brasiliensis tubulin on sodium dodecyl sulfate-polyacrylamide gel electrophoresis was similar to that of rat brain tubulin. The isoelectric range for N. brasiliensis alpha- and beta-tubulin isoforms was pH 5.4-4.8 and pH 4.8-4.7, respectively. However, for rat brain the corresponding ranges were pH 5.4-4.9 and pH 5.0-4.6, respectively. Western blots with anti-tubulin monoclonal antibodies revealed 8 isoforms of alpha-tubulin and 3 isoforms of beta-tubulin for N. brasiliensis and 14-15 and 7-8 isoforms for rat brain alpha- and beta-tubulins, respectively. Different peptide maps were obtained for N. brasiliensis tubulin compared with rat brain tubulin.