Objective: Evaluation nutritional statusamong new cancer patients under 5 years old. Methods: Descriptive, prospective study from September 2016 to September 2017 at the Oncology department, National Children’s Hospital. Results: There were 170 new cases with cancer under 5 years old.The prevanlence of underweight malnutrionwas 22.4% (moderate 20%, severe 2.4%). The prevanlence of stunting malnutrion was 12.4% (moderate 11.8%, severe 0.6%). The prevanlence of wasting malnutrion was 17.6% (modarate 12.4%, severe 5.3%).The prevanlence of malnutrion according to middle upper arm circumference (MUAC) was 10.9%. The prevanlence of overweight by weight/height index was 4.1%. The prevanlence of malnutrion according to serum albumin was 29% and serum protein was 20%. There was not any differences in underweight status between the cancer diseases. Conclusions: The prevanlence of malnutrition ranged from 10.9 to 29% of new cancer patients under 5 years old, according toeither anthropometric index orbiochemical profiles, and was not different between solid tumors and acute leukemia.