Effect of nickel (Ni) on human organism is still evaluated, although there are few research papers dedicated to this problem. The participation of Ni in carcinogenesis and allergic reactions is considered. Nickel is absorbed through the alimentary tract, lungs and skin. Concentration of Ni in blood and urine is low (about 1 μg L-1). More nickel has been determined in tissues such as liver, lungs and osseous tissue. The aim of this work was to assess the Ni level in human hair (n = 220, 110 women and 110 men) and correlations between Ni and other elements i.e. calcium (Ca), magnesium (Mg), zinc (Zn), iron (Fe), lead (Pb), and cadmium (Cd). Hair washed with acetone and redistilled water was mineralized in mixture of HNO3 and HClO4 acids. Content of the elements was determined by the atomic absorption spectrometry method AAS. Concentrations of Ca, Mg, Zn, Cu, and Fe was measured by the flame technique (FAAS), while concentration of Pb, Cd and Ni was analyzed by the electrothermal atomic absorption spectrometry in a graphite furnace (GFAAS). The data were the subject of statistical analysis. The mean Ni concentration in the hair samples was 0.24 μg g-1 (median 0.17 μg g-1, range 0.01-1.77 μg g-1). Slightly more Ni was found in hair of women (0.25 μg g-1) than of men (0.22 μg g-1). Statistically higher concentrations of Ni were noticed in hair of men > 20 years than in younger men (p