Calcium and magnesium are known to be necessary for the normal function of varioussystems in animal and human organisms. There are many diseases caused by abnormalconcentration of electrolytes, e.g. arterial hypertension or nervous system diseases such asmultiple sclerosis, Mb. Alzheimer or Mb. Parkinson. The mechanisms of homeostasis indicateonly the ionized forms of these elements. It is known that ionized calcium serves asan endocellular intermediary in action of enzymes and hormones in cells.Therefore, it is very important to define levels of total and ionized forms of Ca2+ and Mg2+ in blood serum and saliva by the method of atomic absorption spectrometry and toshow their diagnostic value for various pathological conditions of a human body. The 39 persons, aged 21 to 47 years take part in these investigations.The results of determinations of calcium and magnesium forms present in humanserum and saliva, representing physiological states are presented. The age and daily fluctuationsof Ca2+ and Mg2+ content in serum and saliva were studied by atomic absorptionspectrometry. The levels of non albumin forms of these elements were found by FAAS.The significance of determination of calcium and magnesium levels in serum and salivaunder various pathological conditions (arterial hypertension and osteoporosis) was shown.