Background: Pediatric onco-hematology is not a frequently encountered medical specialty, and it influences everyday life, basic activities, and the immune system, mostly through psychosocial changes, which may affect every individual and their families differently. Anxiety is the most frequently encountered mental health disorder occurring during childhood and adolescence. The effect of stress and anxiety on the immune system is suggested by the fact that stress hormones elevate proinflammatory cytokines and subsequently lower the anti-inflammatory response. Objective: Our main objective was to analyze the relationship between anxiety disturbance and cytokine levels in oncologic pediatric patients from Târgu Mureș in order to answer the following question: does anxiety influence immunity? Material and methods: After testing pediatric oncology patients from the Pediatrics Clinic no. 2 of Târgu Mureș, Romania with the SCARED child test, we took blood samples from each participant. IL-6, IL-10, IL-1β, IL-12p40 and TNF-α levels were evaluated with a Human Cytokine Magnetic Panel using the xMAP technique on Flexmap 3D platform (Luminex Corporation, Austin, USA). C-reactive protein levels were determined with the BN Pro Spec nephelometer with CardioPhase hsCRP (Siemens Healthcare Diagnostics, GmbH, Marburg, Germany) reagent. Results: The 46 pediatric oncology patients had 6 main diagnostic groups, the most frequent pathology was acute leukemia (58.7%) followed by malignant solid tumors (21.74%) and lymphomas (6.52%). In the anxious group (45.65%) we observed 4 of the 5 studied anxiety types: panic disorder, separation, social, and generalized anxiety. We measured the cytokine levels of all the participants from the two main groups: anxious/non-anxious. Statistical analysis (linear regression) showed statistically significant positive correlations in the anxious group related to the IL-1β and IL-6, a moderate/weak correlation related to IL-12p40, as well as a negative moderate correlation between IL-10 values in the anxious group and a positive trend in the non-anxious group. Conclusions: Psycho-oncology is a relatively young specialty with few studies in the last two decades. IL-1β, IL-6, and TNF-α present high levels in anxious patients, while IL-10 and IL-12p40 have low serum levels in mental disorders. C-reactive protein levels are not influenced by anxiety.