Pneumonia is a crucial public health problem in developing countries,including Vietnam. Pneumonia claims the lives of nearly four million under-five children every year in which 99 percent of those deathsare in developing countries. Almost all pneumonia deaths are at the age of less than one as a result of severe illness, late hospital admission, and bacterial resistance. In Vietnam, pneumonia is the second highest cause of under-tive deaths after diarrheal disease. Yearly, each child experiences 1.45 pneumonia episodes and most of them are lessthan three years of age.Among factors influencing the occurrence of pneumonia are undernutrition, improper breastfeeding, air pollution, and poor environmental sanitation, undernutrition is a major cause of pneumonia and is a contributing factor in the duration and severity of this disease. Pneumonia often combines with Protein-Energy Malnutrition (PEM), vitamin A deficiency, anemia and other micronutrient deficiencies.The consequence of pneumonia might have been found as an increased risk of poor nutritional status. Some follow-up studies have documented that respiratory infections made linear growth more diflicult than weight gain. There is still some debate about whether ALRI can lead to poor vitamin A status in community-based and hospital-based studies and the results remain uncertain. Acute lower respiratory infectionwas found associated with lower serum retinol in two cross-sectional clinic studies. By contrast, a cross-sectional study failed to show this association. In addition, a cross-sectional study showed that meninéitis and pneumonia were more common in the presence of anemiain hospitalized infants in Papua New Guinea. However,hematological changes during infection are even less confirmed.