Neuropsychiatric symptoms are common after stroke and are distressing symptoms. They may persist after the acute event and negatively impact rehabilitation, functioning, and patients' quality of life. To elucidate the prevalence and course of neuropsychiatric symptoms in stroke patients during rehabilitation, we prospectively investigated the trajectory change of neuropsychiatric symptoms and the association between these symptoms and functional recovery. This observational study enrolled 204 stroke patients consecutively admitted to the rehabilitation ward. We administered the Neuropsychiatric Inventory-Nursing Home Version (NPI-NH) for evaluating the neuropsychiatric symptoms (e.g., apathy and depression) and the Functional Independence Measure (FIM) and Montebello Rehabilitation Factor Score (MRFS) for functional recovery. The cumulative prevalence of neuropsychiatric symptoms was 48% during hospitalization; depression, anxiety, and sleep disturbances were most frequent. Binomial logistic regression analyses revealed that the factors associated with deterioration of neuropsychiatric symptoms during hospitalization included premorbid depression (odds ratio: 18.628, P =.001), the length of stay from onset to rehabilitation ward admission (odds ratio: 1.022, P =.012), motor FIM at admission (odds ratio: 0.950, P <.001), and NPI-NH at admission (odds ratio: 0.923, P =.011). Stepwise multiple regression analyses revealed that the NPI-NH at admission was associated with the MRFS (β = −0.128, P =.037). Neuropsychiatric symptoms are common in stroke patients undergoing rehabilitation and have a substantially negative impact on rehabilitation outcomes. Stroke patients with prolonged acute-phase hospitalization and low functioning at admission must be monitored to detect any deterioration in the neuropsychiatric state. [ABSTRACT FROM AUTHOR]