The Screening measurements of radon concentration were carried out during the period July-October 1990 by means of the passive activated charcoal device in a total of the 160 sites in various buildings in Hong Kong. The arithmetic mean of the measured indoor radon concentrations is equal to 40.0Bq/m~3. Based on above experiment CR-39 unclear track detectors and LiF thermolumin- escence detectors were used to measure the average radon concentrations and gamma radiation dose rates in air respectively, over a period of three months (Feb.-Apr. 1991)ina total 71 sites which were selected from dwellings and work places in Hong Kong. The normal distributions have been obtained from these results. The arithmetic means of the indoos average radon concentrations in dwellings and working places were found to be 72.2Bq/m~3 and 155.4Bq/m~3 respectively, while thearithmetic means of gamma radiation dose rates were determined to be 213.0 nGy/h and 198.1 nGy/h respectively.