This study presents results of a complex survey about residential, soil and water radon in the North of Mureş county (Romania). Indoor radon measurements were performed by using CR-39 track detectors, while radon concentrations in soil and in water were measured by using the LUK3C device and accessories. The indoor radon concentrations of 157 houses ranged from 9 to 414 Bq m-3, with an arithmetic mean of 131 Bq m-3 and a geometric mean of 105 Bq m-3. In ~3.2% of the investigated houses exceed the recommended reference level of 300 Bq m-3. The soil gas radon concentrations in 137 sampling points varied from 5.0 to 88.0 kBq m-3, with a geometric mean of 14.6 kBq m-3. Results of 190 water samples shows radon concentrations from 0.2 to 28.0 Bq L-1, with a geometric mean of 5.0 Bq L-1. Beside these results, indoor, soil and water radon maps were performed, divided into cells of 5 km × 5 km.