Abstract. Aluminum (Al) is an omnipresent non-essential trace element in the human environment; the risk of environmental Al exposure to the general population is on the rise world-wide. We have already shown that hair aluminum (H Al ) is a reliable long-term biological indicator of exposure to aluminum by the human body whereas whole blood is a short-term biological indicator. The aim of this paper is to assess the population Al exposure risk in the Croatian general population by analyzing H Al in 1,073 apparently healthy persons ( ♂ n = 339 and ♀ n = 734) with the ICP MS; H Al median (µg∙g –1 ) was higher in men (7.64) than in women (6.18) (p < 0.01, χ 2 -test). We used the logistic bioassay sigmoid curve of median derivatives to analyze the natural distribution of Al in hair. The physiologically tolerable range, i.e., the linear part of the sigmoid curve, was 1.83 – 20.9 µg∙g –1 in women and 2.39 – 27.7 µg∙g –1 in men. Hair Al concentrations below or above this tolerable range indicate negligible low or excessively high Al exposure, respectively. Our results indicate that currently ~ 6% of Croatian men and women are overexposed to aluminum to a various degree.