Background: The radioactivity levels in sediment and rock samples of İkizdere and Kaptanpaşa Valley have been determined. To our knowledge, there seems to be no information about radioactivity level in the İkizdere and Kaptanpaşa Valley sediments and rocks so far. Materials and Methods: The average radium equivalent activity (Raeq), the total absorbed dose rate (D), the external risk index (Hex) and the annual effective dose equivalent (AEDE) which will be defined later have been calculated and compared with the results in literature. Rock characterization was also investigated using thin section and X-ray diffraction (XRD) analysis. Also gross &alpha and &beta activity concentrations were calculated for some rock samples. Results: Their radiological implications were also calculated and compared with the international recommended values. The gross &alpha activity is generally lower than the corresponding gross &beta activity for some rock samples. Rock characterization was also investigated using thin section and XRD analysis. Conclusion: This study can be used as a baseline for future investigations and the data obtained in this study may be useful for natural radioactivity mapping. It seems necessary to determine the radioactivity concentrations in sediments and rock of other parts of Turkey. The results may also be used as a reference data for monitoring possible radioactivity pollutions in future.