The mineral content (Al, As, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, Ge, Hg, I, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, S, Se, Si, Sn, Sr, Zn) of hair in 42 Arabian mares (aged 4-15 years, kept in the same management and feeding conditions) was assessed and it was analysed in particular sire and dam lines. The method of atomic emission measurement with optic spectroscopy technique was used. Significant differences in calcium and copper level between mares in particular sire lines were found. The analysis of the elements’ concentration in mares of particular dam lines showed significant changes in cobalt and arsenic levels. It may be stated that the genealogical affinity can have a modifying influence on some bio-elements’ content in the hair.