Critically ill patients admitted in ICU and NCU were studied with respect to their nutritional status and support to them at initial period, and the effect of nutritional support after 3 weeks. The nutritional support was supplied to these patients with the enteral and parenteral nutrition. The results of biochemical test and status of nutritional support on 52(29 males, 23 females) critically ill patients were based on medical records and the anthropometry was measured on 28 patients. The subjects were in mild malnutrition. Their initial calorie intakes were 85% of BEE, 57% of total energy requirements and 49% of protein requirement were provided. Two groups, one group of serum albumin level more than 3.5g/dl and the other group of serum albumin level less than 3.5g/dl, were significant different in total calorie and protein intakes. After 3 weeks, inappropriate nutritional support in the group of normal nutrition results in significant decreasing of serum albumin level but, there were no changes in the group of malnutrition. Nutritional support is one of the mainstays in the management of these critically ill patients and is aimed at preventing malnutrition. Therefore, timely nutritional support is heavily required in cases of critically ill patients whether their initial nutritional status is normal or not.