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/l 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 Balıkesir 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.