To evaluate the implementation of the World Health Organization guidelines for the treatment of children with severe acute malnutrition in a class I hospital.Descriptive and prospective study of 335 children under the age of 6, admitted between 2001 and 2005 for severe acute malnutrition (83%) and moderate acute malnutrition associated with illness (17%). The care of the children was provided by clinicians and medical staff trained under World Health Organization guidelines.Kwashiorkor was a common result in children with severe acute malnutrition (60.8%); 58% were younger than 1 year old. Complications upon admission were diarrhea (68.4%) and anemia (51.1%), and the most common complication during hospital stay was sepsis (9%). Overall, 61.7% attained -1 standard deviation of weight for height after an average stay of 3 weeks in the hospital; 5.1% were sent to tertiary care hospitals. Overall, mortality during the 5 years was 5.7%, with sepsis the most common cause. In the first year, the mortality rate was 8.7%; it decreased to 4.0% in the last year. The mortality rate was significantly higher in children with edema. Children with moderate acute malnutrition had similar complications and mortality when compared with children with severe acute malnutrition (5.3%).Once the World Health Organization guidelines were implemented, low mortality rates were achieved in children with severe acute malnutrition in class I hospitals.