The radioactive gas radon is ubiquitously present in our earth's environments. The radon is one of the health hazard radioactive elements for humans. Main objectives of the present study are to focus how radon is concentrates in indoor and outdoor environments and to find relationship between radon exposure and incidence of some malignant and non-malignant diseases in human body. To obtain basic information on radon and to find risks of occurrence of some feasible diseases associated to radon exposure, this study reviewed different published literatures reporting the sources of radon, radon entry in indoor and outdoor environments, factors influencing the radon concentrations, and induced health effects associated to radon and its decay products. From these studies, required information and supporting data have been extracted and then used in the present study. Present study provides some valuable information regarding the radon exposure and evidences of some health effects caused by radon and its decay products. This can help to both researchers and general population.