In this work, Radon (222Rn) concentrations in groundwater, were measured Al- Najaf city, using the RAD-7 radon monitoring system of Durridge company the USA and CR-39 detector. Each location was determined on the map by using GIS program. The annual effective dose for all samples of groundwater was calculated by equations depending on the UNSCEAR organization.It is found that the average of the radon concentrations in groundwater samples using RAD-7 were varied from (174.5 ± 24.242 Bq/m3) to (2000.5 ± 165.8 Bq/m3), but using CR-39 varied from (179.101 ± 55.286 Bq/m3) to (557.772 ± 166.546 Bq/m3). Also, the results showed that annual effective dose in all groundwater samples was lower than the permissible limit of (1 mSv) recommended by ICRP 1993. The correlation of radon concentrations in present study using active technique (RAD-7) and passive technique (CR-39) is very good significant showing a linear correlation coefficient of (0.80). Certainly, this study was conducted to provide a health-oriented radon assessment of Al-Najaf cities, address long term management goals, especially from the environmental point of view. The results provide a framework for future studies that should include a large and broader survey of radon concentration in Iraq.