Class Pi glutathione S-transferase was purified to homogeneity from pig lens cytosol. This enzyme was composed of two identical 22 kDa subunits and had isoelectric point of 8.5 from the results of SDS gel electrophoresis, gel filtration, amino acid sequence analysis and isoelectric focusing. Amino acid sequence of N-terminal 15 residues was almost identical to class Pi enzymes from human, rat and mouse. Antibody against the pig enzyme crossreacted to human glutathione S-transferase-pi and anti-rat glutathione S-transferase-P antibody crossreacted to pig enzyme.