This is a one-year follow-up study looking into the nutritional status and the rate of re-hospitalizations in children at the UHC Zagreb, Dept. of Paediatrics who were first evaluated during the nutritionDay (nDay) in November 2018. The aim is to evaluate the accuracy of STRONGkids questionnaires, subjective assessment within nDay survey and anthropometry in detecting malnutrition and possible relation to number of hospital admissions and disease outcomes (for oncology patients) within a year.The study included 50 patients (mean age 13.48 years ±3.79, 22 males) whose nutritional status was estimated in November 2018. Additional data were collected after the period of 12 months. Mann-Whitney U, Kruskal Wallis and Wilcoxon signed-ranks tests were applied.A significantly different BMI was found among subgroups categorized through the nDay survey (without risk, at risk, malnourished patients) and among subgroups assessed by STRONGkids (low, medium and high risk for malnutrition) (p1=0.002, p2=0.003, resp.). Post hoc tests showed that statistical significance could be contributed to differences between groups malnourished patients vs. those not at risk within nDay (p3=0.009) and between groups low vs. high and medium vs. high risk defined through STRONGkids questionnaires (p4=0.020, p5=0.004, resp.). In the one-year follow-up period, 28/50 children were re-hospitalized once or several times.The number of re-hospitalizations was significantly higher for children classified by STRONGkids to have high risk for malnutrition (p6=0.002), as well as for those categorized as malnourished through the nDay survey (p7=0.024). No significant difference in z-score BMI values was found between years 2018 and 2019 (Wilcoxon signed-rank test: p8=0.086).Re-hospitalized oncology patients (11) were additionally analysed in respect of their disease status: favourable outcome (disease regression; 8/11) vs.unfavourable outcome (progression or unchanged state; 3/11). No difference was observed in the initial BMI between these groups (Mann-Whitney U test: p9=0.921), and no significant change in their BMI during this period was observed in either group (Wilcoxon signed-rank test: p10=0.161, p11=0.593).Patients categorized as malnourished both with STRONGkids and nDay survey had significantly lower BMI than the rest of subjects. Our data support the hypothesis that malnourished patients have a higher rate of re-hospitalizations. Within the observational period, re-hospitalized patients neither improved nor worsened their nutritional status according to the BMI z-scores. We were not able to connect the nutritional status of oncology patients with their disease outcome after one year, perhaps due to a rather small sample or short time of follow-up.