Although, the safe limits of human daily boron (B) exposure are not absolutely clear, there is a growing interest in B and its effects on human health. The aim of the present study was to estimate daily B exposure in 66 males in Turkey living in a B-rich area using water containing at least 2 mg/1 boron, with an average age of 38-55 (SE 1.66) years and an average number of years of residence in the B-rich area of 35-89 (SE 1.73). Another group of males (n 57), living in the city centres of Balikesir and Ankara, were taken as controls; the average age and number of years of residence for this group were 29-44 (SE 1-43) and 10-26 (SE 1.83) years, respectively. As it is assumed that the B level in urine reflects daily B exposure, the amount of urinary B of both the study and control groups was analysed by using an inductively coupled plasma optical emission spectrometry (ICP-OES) technique. The average daily B exposure value was calculated as 6.77 (SE 0.47) mg in the study group and 1.26 (SE 0-1) mg in the controls. The results of this study are expected to contribute to creating a reference value for a safe daily B exposure.