We investigated the effect of hypodermosis on the quantitative and some qualitative indicators of milk from 20 experimental and 18 control first-calvers of the Pinzgau cattle breed. The experiment took place at two experimental localities in mountainous pastures of the Central-Slovakian region. In the experimental animals, treated with Hypocid, the production of milk per dairy cow increased on an average by 115.98 kg, i.e. 24.83%, over the experimental period of 61 days (May, June) with an average invasion intensity of 5.94 larvas in control animals. Milk fat production increased on an average by 7.20 kg, i.e. 34.97%. Production recalculated to FCM milk amounted on an average to 31.61%. The profitability of treating hypodermosis with the Hypocid preparation is expressed by the average savings of 0.40 Kcs per litre of milk per day.