This study investigated the basic knowledge levels of teacher candidates from different branches regarding the subjects of radiation and radioactivity. 42 variables were determined in relation to the specified titles. In the preparation stage of determining the variables, all the related programs were examined, and attention was paid to include the subject matters the students study in the related lessons and those from daily life. A questionnaire form including 20 close-ended questions belonging to the five specified variables was prepared and gathered under the following five factors. Definitions, kinds and sources of radiation and radioactivity, basic concepts concerning radiation and radioactivity, interaction of radiation with substance, effects of radiation on living things and usage areas of radiation. According to the analysis, a significant difference between the teacher candidates of the elementary education division and other two groups was observed. (Contains 7 tables.)