One of the most important factors that determine the growth pace of professions, and of science in the wider sense, takes places through the effective sharing of the professional knowledge by the individuals from various fields of profession. However, it is also known that those individuals who possess knowledge are inclined to hide it, instead of sharing it, due to various reasons. Therefore, the studies devoted to the examination of the factors affecting the knowledge sharing behavior at the individual level positively or negatively are vital to the humanity. In the study carried out by this motivation, the Theory of Planned Behavior and Social Exchange Theory were appropriated as the theoretical frameworks, and based on these, the relationships among "expectation of personal output", "expectation of loss of knowledge power", "expectation of reciprocity", and "attitude towards knowledge sharing" were examined as the factors considered to be affecting the knowledge sharing behavior of individuals. In order to test the research hypotheses, a quantitative investigation was carried out based on the data obtained from physicians from 254 dermatologists across Turkey, among whom the knowledge sharing is of vital importance. Taking the research results into consideration, it has been seen that personal output and reciprocity expectations of dermatologists affect their attitudes towards knowledge sharing positively, whereas their expectations concerning the loss of knowledge power affect their attitudes towards knowledge sharing negatively. Moreover, it has also been observed that the attitude towards knowledge sharing affects the knowledge sharing behavior positively. The results of the study has confirmed the research model and has demonstrated the explanatory powers of the Theory of Planned Behavior and Social Exchange Theory in estimating dermatologists' behavior of knowledge sharing.