Objective: Assessment of fluid and protein intake in patients operated for colorectal cancer in the first five postoperative days. Subjects and methods: Data was collected from 30 patients operated for non-metastatic colorectal cancer at the Surgical Clinic, University Hospital of Split over a period of one year. Body composition was determined with a BIA scale, while serum albumins and proteins were analyzed preoperatively and on the fifth postoperative day. During that period, an informative interview was conducted on food, liquid and nutritional support intake. Results: Compared to the preoperative day, on the fifth postoperative day, no significant difference was found in the body composition, as well as the values of the laboratory results, except for the increase in serum albumin values. Patients consumed a significantly lower amount of protein than their calculated needs on all five postoperative days. Fluid intake was highest on the first and lowest on the fifth postoperative day. On all five postoperative days, the amount of fluid intake was less than their calculated needs. Discussion: Patients did not consume a sufficient amount of protein and fluid in the postoperative period, which matches with the results of similar studies. We attribute the reduced fluid intake to restrictive intravenous fluids as part of the ERAS protocol. An increase in the value of serum albumins is possible due to the administration of intravenous solutions of human albumins to prevent postoperative complications. Conclusion: The intake of protein and clear liquids in the first five postoperative days after colorectal cancer surgery is not in accordance with the calculated needs of patients.