The free-living nematode Panagrellus redivivus was found to have relatively high cytosolic glutathione transferase activity. Chromatofocusing indicated that at least four GSH transferase forms were present in the nematode cytosol. An endogenous molecular factor interfered with the binding of the cytosolic GSH transferases to a glutathione affinity matrix and binding only occurred after a partial purification step. The major resolved GSH transferase form B was a basic enzyme that showed no biochemical homology to the three mammalian multigene GSH transferase families and appeared to interact with plant phenols, possible natural substrates. A minor GSH transferase form AT showed a biochemical relationship to the mammalian α family including catalytic activity with a model lipid hydroperoxide substrate.