Isocitrate lyase and malate synthetase, key enzymes of the glyoxylate cycle, were present in postparasites of the mermithid nematode Romanomermis culicivorax. Specific activities of enzymes were higher in adult postparasites than in newly emerged juveniles. Isocitrate lyase had a well-defined pH optimum (7.5), whereas malate synthetase functioned optimally over a broad range of alkaline pH (7.5-9.0). Substrate affinities of the two enzymes were measured. Key words: glyoxylate pathway, isocitrate lyase, malate synthetase, physiology, postparasite, Romanomermis culicivorax.