Descriptive cross-sectional study, conducted among 644 adult patients hospitalized in three hospitals in Kinshasa. 231 patients were undernourished, for a prevalence of 36%. It is highest in the 40 to 49 age group (26.4%). It increases hospital stays between 45-69 days in 43.9% of patients. It affects both sexes (p = 0.781). Persistence of inflammation (p <0.05), reduction of ingesta (p <0.05), protein deficit linked to the action of catabolism and cytokines (p <0.05), increased protein-energy expenditure during infectious, inflammatory, traumatic states and the absence of nutritional treatment (95% of cases) did not lead to an improvement in the nutritional state of the patients followed. Care practices are characterized by the lack of organization of nutrition and food services; the absence of policies, screening strategies and management of undernutrition. Undernutrition goes unnoticed and underestimated. The creation of a Clinical Food and Nutrition Service is urgently needed. National health policy attention remains necessary.