The studies on biological control of damson-hop aphid (Phorodon humuli Schrank) on Marynka cultivar, using Aphidius colemani and Aphidoletes aphidimyza, were carried out in the hop-garden localised within Hop Experimental Station at Jastków over the years 1998–2000. The efficacy of Aphidius colemani ranged from 5% to 65% and was found sufficient to control damson-hop aphid in the period before flowering i.e. to the middle of July, but it was not sufficient later. The efficacy of Aphidoletes aphidimyza ranged from 50% to above 90% and it was sufficient in one of the examined vegetation seasons. High air temperature and lack of rainfall reduced efficacy of both species, but especially that of Aphidius colemani.