Objective: To compare the radiovisiography (RVG) with the clearing technique using Kappa value in the study of the root canal types. Methods: One hundred recently extracted human maxillary first premolars were used. Standard periapical RVG images were taken from a buccolingual and mesiodistal direction. The specimens were then accessed, injected with ink, demineralized,dehydrated, and finally were cleared. The RVG images and the transparent teeth were examined by a trained endodontist, and the date of root canal types following Wu's classification was collected. Results: The reliability of RVG was high for studies on simple root canals,but was poor for the studies on the multiple root canals. The Kappa value between the two techniques was 0.3793, indicating the agreement was poor. Conclusion: It is concluded that the limited value of RVG alone when studying certain aspect of the root canal system. The resolution of the RVG system should be enhanced.