Acute lymphoblastic leukemia (ALL) is the most common malignancy in children and is usually associated with numerical and structural chromosomal changes. Although some of these changes are accepted as favorable or poor prognostic factors, the prognostic effects of others have not been well determined. In our study, we aimed to present the chromosomal changes in cases with childhood ALL and their ratios in hematologic risk groups. Thirty four patients with childhood ALL were included in the study. Subjects were diagnosed with fluorescence in situ hybridization (FISH) analysis by using standard translocation, deletion and aneuploidy probes. The chromosomal changes obtained from our analysis were classified into hematologic risk groups and their ratios were evaluated. In our study, we found that the t(12.21) translocation was the most common abnormality in minimal and standard risk groups, whereas the 9p21 deletion was the most common abnormality among high-risk patients.