Cancer patients are particularly susceptible to nutritional depletion. From March 2014 to December 2015, we assessed 146 patients consecutively hospitalized in a tertiary emergency pediatric hospital. The patients were divided into 2 groups: group I, patients with cancer (43 patients), and group II, the control group consisting of 103 age-matched and sex-matched healthy patients. The anthropometric parameters (weight-W, height-H, body mass index [BMI], middle upper arm circumference [MUAC], tricipital skinfold thickness [TST]) and biochemical parameters (proteins, albumin) were comparatively evaluated. Fat mass (FM, kg and %), fat-free mass (FFM, kg), muscle mass (MM, kg), and total body water (TBW, %) were measured in both groups using Tanita BC 420 S MA Analyzer. Anthropometric and biochemical parameters in group I were significantly different from those in group II for weight, height, BMI, MUAC, TST, protein, and albumin (P<0.05). In the study group, FM was much lower compared with controls 16.9% (3.4% to 33.3%) versus 20.3% (6.6% to 38.4%); (P=0.001), and TBW was much higher 60.8% (48.8% to 70.6%) versus 58.5% (45.2% to 68.6%) (P=0.004). FFM and MM were not statistically different in the 2 groups. The results highlight the complex changes of nutritional status in pediatric patients with cancer.