We hypothesize that Pittsburgh compound B (PIB) binding is common in poststroke dementia (PSD) and that cognitive decline may be faster in PIB positive patients. We performed PIB positron emission tomography (PET) among 17 subjects: 10 PSD patients, 4 Alzheimer's disease (AD) patients, and 3 healthy controls. We also compared the rate of change in mini-mental state examination (MMSE) between PIB positive and negative patients. We detected AD-like PIB binding in 4 PSD patients (40%), all the AD patients, and 1 healthy control. The global PIB retention standardized uptake value (SUV) at 35-45 min for PIB positive stroke patients was 1.67 (range 1.56-1.82), which was similar to the AD patients (1.65; range 1.46-1.88) and was lower than PIB negative patients (1.29, range 1.24-1.34). Mean annual MMSE decline for the 4 PIB positive patients was 2.9 and that for the 6 PIB negative patients was 1. This pilot study suggests that PIB PET is feasible for the evaluation of PSD and PIB binding may be common in PSD. Whether presence of PIB binding is associated with a more rapid cognitive decline in PSD requires further study to confirm.