The aim of this work was to obtain comparative evaluation of the content of calcium (both the total and ionic forms), magnesium and phosphorus in the blood serum of goats during three physiological states characterized by much instability of the mineral balance. The study involved 15 goats, divided into 3 groups in different physiological states (breeding season, pregnancy, lactation period). The study showed that the mean content of the ionic form of calcium (A,D – 1.210; B,E – 1.135; C,F – 1.115) and total calcium (A,D –1.640; B,E – 2.075; C,F – 2.045) in all the groups was within the range reference concentrations. It can be thought that the low content of calcium was caused by its deficiency in fodder and unstable hormonal balance (pregnancy and lactation period). The reason why the mean content of calcium did not reach the reference level for this species was a high content of P (A,D – 1.650; B,E – 2.040; C,F – 2.125) and Mg (A,D – 0.970; B,E – 1.415; C,F – 0.990) in blood serum.