Soil-gas 222Rn concentrations were investigated on an active Simav Graben/Fault System in Western Turkey. Measurements to understand the causes of variations in soil-gas 222Rn were conducted in three distinct sections such that seven selected measurement points in each section lie on a line that is approximately perpendicular to the main fault line. It was found out in each section that values obtained at two adjacent points were abnormally higher than the rest. The corresponding concentrations were measured as 60.76–63.93 kBq/m3, 33.00–45.78 kBq/m3, and 56.20–84.69 kBq/m3 on the first, second, and third lines, respectively. These values, which differ significantly from measurements conducted on a similar line, are thought to be stemming from crustal stress caused by faulting or acidic-intrusive rocks in the region.