The main objective of the present paper is to explore the effects of radiation exposure on the inhabitants near the Semipalatinsk Nuclear Tests Site (SNTS), Kazakhstan. Our research team of the Research Institute for Radiation Biology and Medicine, Hiroshima University, started in 2002 to conduct a field research study using questionnaire surveys. The present paper attempts to clarify health effects and mental problems on the inhabitants by using our questionnaire surveys. Among the responses to our survey, the present paper focuses upon responses to the questions concerning their health and mental problems. The data in Semipalatinsk have been compared with the results obtained in a similar survey conducted by Hiroshima and Nagasaki cities. The results show: (1) 33% of the residents replied that they felt bad or had very bad health conditions. (2) 70% of the residents strongly recognized a causal relationship between their bad health conditions and the nuclear tests. (3) The diseases that over 30% of respondents possessed are arthralgia/ lower back pain/ arthritis, high-blood pressure, heart disease and digestive system disease. (4) Acute radiation injuries from 1949 to 1962 that over 20% of respondents experienced were headaches and general malaise. (5) Concerning their mental condition, 22% of respondents felt easily frustrated and agitated and 21% experienced nightmare.