Arsenic is one of the most deleterious trace elements due essentially to its carcinogenicity resulting in the development of internal malignancies and skin cancer. In this study, arsenic concentrations of soils and stream waters in an area where the world class borate deposits of Turkey occur are presented. Soil and stream water samples were collected from the Emet basin of Neogene age, where intense borate mining activities have been practiced for about 60 years. Inductively coupled plasma-mass spectrometry (ICP-MS) was employed to analyze arsenic concentrations in soils and Gutzeit Method for water samples. As concentration levels in soils and waters ranged from 0.4 up to 2488.4 mg kg(-1) (mean 111.8 +/- 200.1 SD) and from 8 to 243 lg/L (mean 96.63 +/- 66.83 SD), respectively. While soil pH measurements varied between 5.97 and 7.75 (avg. 7.06 +/- 0.56), water pH values ranged from 6.44 to 8.32 (avg. 7.734 +/- 0.59). As contents of both soils and surface waters were significantly (few tens to thousands times) high exceeding the maximum contaminant levels of current US-EPA's maximum contaminant level of 0.01 mg As/L. Western Anatolian young (down to about 1 my) volcanic activities and shallow intrusive emplacements resulted in the formation of considerable number of geothermal and hydrothermal systems and kept them active for long enough that gave rise not only to the formation of numerous epithermal mineralizations rich in As-Sb-Hg-bearing sulfide minerals, but also to the formation of As-enriched sedimentary and magmatic rocks. Their dissolution and redistribution within the rocks and resultant soils consequently made them geogenically As-rich.