Although it is well known that cancer patients suffer from malnutrition, there are few published studies on malnutrition in outpatients receiving chemotherapy in Korea. This study aimed to evaluate nutritional risk in oncology outpatients receiving chemotherapy and to show the baseline data to set up nutritional management programs for cancer patients. This is a retrospective observational analysis on 1,962 patients referred for nutritional education before or during chemotherapy at Seoul National University Hospital Cancer Center from January 2006 to May 2007. According to a malnutrition screening tool, the proportion of patients having malnutrition risk was 23.0%. In the case of upper gastrointestinal cancer, more than 50% of patients were assessed as being at the risk of malnutrition. They showed more than 7% weight loss compared to their usual body weight and poor oral intake; energy intake was less than 100% of Basal Energy Expenditure(BEE) and protein intake was less than or equal to 0.77 g/kg/d. However, only 6.3% of breast cancer patients had risk of malnutrition and their oral intake was better; energy intake was 121% of BEE, and protein intake was 0.90 g/kg/d. Outpatients receiving chemotherapy had different nutritional risk depending on their cancer site. Nutritional management program should be conducted differently, depending on the cancer site and upper gastrointestinal cancer patients at high risk of malnutrition should basically have nutritional assessment and intervention.