We assessed which nutrition evaluation method [subjective global assessment (SGA); malnutrition universal screening tool (MUST); nutritional risk index (NRI)] provided the most efficacious combination of high validity, low cost, and ease of use to examine and improve the status of malnutrition for colorectal cancer (CRC) patients. The SGA, MUST, and NRI scales were used to analyze the preoperative status of malnutrition for 45 CRC patients in a medical center in Taiwan. Differences in the reliability of the 3 methods were compared using the kappa (κ) coefficient of agreement. Lengths of hospital stays were compared using the Mann-Whitney U test to examine the effect of malnutrition in CRC patients. The SGA κ coefficient was higher with the MUST than with the NRI. Preoperative and postoperative weight losses were significantly different on the NRI, and the longer the length of the hospital stay, the greater was the weight loss. Although the SGA had a higher validity and lower cost than the NRI, we recommend using the MUST method for a routine nutrition evaluation because it is easier to use and is less expensive than the SGA and the NRI.