A number of methods exist that allow in a smaller or larger degree to estimate the composition and build of the man’s body.  To the most popular possible methods following can be numbered: measuring of body weight, anthropometric research (in the composition of which enters even the measurement of growth or circumferences of separate body parts), deduction of the BMI index. The mentioned methods carry with itself the risk of an error and does not allow to receive the detailed state information, body condition and patient’s health parameters.  The method of electric bio-impedance can appear in the decision of the above-mentioned problems, due to that received information about composition of patient’s body it is easier to create an effective nourishing plan and a corresponding diet [3]. This publication characterizes the BIA method, presents methodology of realizations of measuring and their interpretation.