This prospective study presents the prevalence and risk factors of malnutrition in 49 consecutive stroke patients on the rehabilitation (Rehab) service and at 2- to 4-month follow-up. Malnutrition was diagnosed using biochemical and anthropometric data. Stroke patients, on admission to Rehab, have a very high prevalence of malnutrition. Malnutrition, 49% on admission, declined to 34%, 22%, and 19% at 1 month, 2 months, and follow-up, respectively. Dysphagia, 47% on admission, was associated with malnutrition (p = .032) and significantly declined over time. Using logistic regression, predictors of malnutrition on admission involved acute service tube feedings (p = .002) and histories of diabetes (p = .027) and prior stroke (p = .013). Tube feedings, associated with malnutrition on admission (p = .043), were more prevalent in brain stem lesion patients. Patients tube fed > or = 1 month during rehabilitation or at home were not malnourished. Malnutrition was associated with advanced (> 70 years) age at 1 month (p = .002) and weight loss (p = .011) and lack of community care (p = .006) at follow-up. Early and ongoing detection and treatment of malnutrition are recommended during rehabilitation of stroke patients both on the service and at follow-up.