Calcium and magnesium are known to be necessary for the normal function of various systems in animal and human organisms. There are many diseases caused by abnormal concentration of electrolytes, e.g. arterial hypertension or nervous system diseases such as multiple sclerosis, Mb. Alzheimer or Mb. Parkinson. The mechanisms of homeostasis indicate only the ionized forms of these elements. It is known that ionized calcium serves as an 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 to show 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 human serum and saliva, representing physiological states are presented. The age and daily fluctuations of Ca2+ and Mg2+ content in serum and saliva were studied by atomic absorption spectrometry. 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 saliva under various pathological conditions (arterial hypertension and osteoporosis) was shown.