Conclusions. The high prevalence of malnutrition among recently admitted hospitalized pediatric and adult patients determined in this study reinforces the need for a tool to identify risk of malnutrition among pediatric and adult patients admitted to Lao hospitals. Our results also indicate that implementing a nutrition risk screening tool in the national hospitals in Vientiane, Lao PDR is feasible. Nutrition screening and efforts to address hospital-based malnutrition may be more important in certain wards with high rates of malnutrition such as the diabetes, pulmonary, internal medicine, and infectious disease wards. Timely identification of malnutrition among newly admitted hospitalized patients will help minimize adverse patient health outcomes and reduce the economic burden of healthcare in Lao, PDR.