There have been no data on the performance of the Initiation-Perseveration subtest of the Mattis Dementia Rating Scale (MDRS-IP) in screening poststroke dementia (PSDE). Three months after the index stroke, a research assistant administered the MDRS-IP and Mini-Mental State Examination (MMSE) to 83 Chinese stroke patients with lacunar infarcts who were consecutively admitted to the stroke unit of a general hospital. A psychiatrist, who was blind to the MDRS-IP and MMSE scores, interviewed all 83 patients and made a Diagnostic and Statistical Manual of Mental Disorders (4th edition) diagnosis of dementia, which served as the benchmark for judging the performance of MDRSIP. The optimal cutoff point of MDRS-IP was 22/23. The sensitivity, specificity, and positive and negative predictive values of MDRS-IP, and the area under the receiver operating characteristic curve were 82%, 90%, 0.41, 0.98, and 0.91, respectively. The overall performance of the MDRS-IP was comparable to the MMSE.