Economic indicators in the pig production depend greatly on the results in the piglet production. One of the factors which have impact on the piglet production expenses is the period of the use of brood sows. Determining the optimal period of the sow usage is made through the assessment of the optimal number of the achieved farrows. In this paper, calculations of the prices have been made for produced piglets relative to the moment of exclusion from the reproduction process. Calculations show that the optimal period of the use of a sow, from the aspect of the minimal price 6 to 8 parities, while the price of a piglet increases afterwards. The advantage achieved by the high percentage of separation should not be neglected: faster introduction of new lines of gilts and less energy for meeting basic needs. On the other hand, apart from the decrease in the costs, low percentage of separation results in the low percentage of second-farrows, more fatlings per sow, lower percentage of gilts in the progeny, more space required for sows in reproduction stage and less difficulties during the gestation period.