Objectives: This study aimed to compare the reliability and screening ability for Alzheimer`s disease (AD) of five scoring methods of clock drawing test(CDT). Methods: Consecutively recruited 155 probable AD patients and 155 normal control subjects participated in the study. The clock picture drawn by each subject was scored according to five CDT scoring methods, such as the CERAD, Rouleau, Sunderland, Mendez and Todd method. The inter-rater reliability was compared by calculating Pearson`s correlation coefficients. The screening ability was compared by analyzing the receiver operating characteristic(ROC) curves. Results: The five scoring methods had excellent inter-rater reliability in common. In terms of the screening ability for overall AD, there was no difference among the scoring methods. There was also no inter-method difference in screening ability for very mild AD. In contrast, as for the screening of mild to severe AD, the CERAD method showed significantly better ability than the other four methods. Conclusions: Regardless of their complexity, CDT scoring methods appears to have similar screening ability for overall AD. In screening clinically more evident AD except very mild one, however, the CERAD methods, in spite of its simplicity, can be probably applied more usefully than other CDT scoring methods.