Mini-mental-State Examination (MMSE) is a widely used tool for dementia screening. However, several limitations are found and the Rowland Universal Dementia Assessment Scale (RUDAS) appears to be an alternative test. The objective in this study was to compare the performance of MMSE-Thai 2002 and RUDAS-Thai for dementia screening, and to determine their performances and identify their optimal cut-off points. The participants were older patients from a Geriatric and Neurology Outpatient Clinic, Srinagarind Hospital, Khon Kaen University. The RUDAS-Thai and the MMSE-Thai 2002 were administered to each participant. Subsequently, a specialist physician assessed each participant for dementia. Results showed the area under receiver operating characteristic curve for both RUDAS-Thai (81.0%; 95%CI, 74.8-87.2) and MMSE-Thai 2002 (81.2%; 95%CI, 74.9-87.4) were equal. A score of 24 or lower provided an optimal cut-off point. Our finding supports that the RUDAS-Thai can be an effective alternative test for dementia screening. For both test scores, a score of 24 or lower is an optimal cut-off point to provide an indication of developing dementia.