Disturbance of mineral status in patients with chronic renal failure (CRF) is one of many complications of this disease. Trace elements analysis in hair is sometime used by clinicians for a diagnosis of mineral status. In the present study concentration of magnesium and other trace elements was determined in serum, erythrocytes, and hair of patients with CRF undergoing hemodialysis (n = 31) and with impaired renal function but non-dialyzed (n = 15). Measurements of mineral content were performed by the atomic absorption spectrometry method (AAS). In serum of hemodialyzed patients as well as in erythrocytes and hair we found significantly increased levels of almost all tested elements, especially for Mg, Al, and Cr, compared to the control group. No significant differences were observed between these groups only in the Cd content in the examined samples. However, a significant correlation between its concentration in serum and erythrocytes was only found in the case of this element. Hair analysis reflected well the changes of mineral distribution in patients with CRF and may be used to diagnose these anomalies, in particular, with regard to Ca, Mg, Fe, and Cr. However, a strong variability of the concentration for these elements was found. In conclusion, our results confirm that renal failure as well as dialysis provoke imbalances of elemental status in physiological fluids and tissues, which should be monitored.