The effect of parathion-methyl at 200 g a.i./ha on predators and parasitoids of soyabean pests and the prey-predator relationship was studied in Rio Grande do Sul, Brazil, during 1986-87. A total of 1 1.5% of live larvae collected and IO% of dead larvae were parasitized. All parasitoids of live larvae (Patelloa sp., Litomastix sp., Microcharops sp. and Euplectrus sp.) emerged successfully. However, only 12.5% of parasitoids emerged from dead parasitised larvae, with Pateloa sp. and Euplectus sp. being the most affected. It was concluded that the insecticide had a limited effect on the beneficial fauna and mortality of parasitised larvae was not total. none