The present work contains data obtained during the analysis of blood samples obtained from patients (number: 102, age: 0–2 years old) with confirmed acute lymphoblastic leukemia diagnosis. Among these total number, 48 patients who received a chemotherapy including 9 patients with side-effects were chosen. Final data include a table of protein masses (biomarkers of pathological processes at the chemotherapy) obtained by the MALDI-TOF spectroscopy from blood of 9 chosen patients (0–2 years old).