In the literature, studies showed that self-efficacy of cancer patients are related to their quality of life in different domains. Considering the need of a scale measuring cancer related self-efficacy in Turkish culture, the objective of the current study was to examine psychometric reliability and validity of Cancer Behavior Inventory (CBI) in Turkish cancer patients. One-hundred and twenty cancer patients participated in the study. In addition to CBI, participants were administered Beck Depression Inventory, Multidimensional Quality of Life Scale - Cancer, Ways of Coping Inventory, Life Orientation Test-Revised, and General Self-Efficacy Scale to test the validity of the adapted scale. The results showed that the CBI has a four-factor structure in Turkish culture. The internal consistency of the scale was .91 and the internal consistencies of subscales ranged between .70 and .90. The validity scores of the scale were also satisfactory. The regression analysis revealed that the CBI predicts the patients' quality of life better than General Self-efficacy Scale. CBI is a valid and reliable measure. As compared to general self-efficacy measures, CBI provides more precise information about cancer patients' QOL. The results, directions for future studies and limitations were discussed in the light of the literature.