The author's results of the research on the relationship of aphid parasites to aphid attending ants based both on the study of taxonomy and ecology of the parasites (Hym., Aphidiidæ) have shown that the parasites are disregarded by the aphid attending ants. The ant attendance of the host aphid does not influence the parasite specificity. In biological control praxis, in case of experiments on introduced parasites of pest aphid establishment, the ant attendance, however, is but recommended to be also considered.