Acute lymphoblastic leukemia (ALL) is a malignant disorderresulting from a clonal proliferation and accumulation of progenitors thatexhibit all markers associated with the earliest stages of lymphoidmaturation. DNA methylation is one of mechanisms involved inepigenetic silencing; The short arm of chromosome 11 has been a focusof special interest with regard to methylation in cancer. The calcitonin(CALCA) gene is located in this area in band 11p15.We have studied the human calcitonin gene methylation in 30 denovo pediatric ALL patients using methylation specific PCR (MSP) andcorrelated this hypermethylation with the clinical presentation, laboratorydata and clinical outcome after induction therapy protocols and shorttermfollow up for 6 months later and we found that DNA methylationwas considerably more common in ALL patients than normal individuals(p = 0.02); percentage of ALL patients with methylated CALCA genewas 56.7% versus 43.3% of patients having unmethylated gene, while incontrol individuals; only 20% had methylated gene versus 80% havingunmethylated gene. Clinical, laboratory and molecular features didn’tdiffer significantly between those with methylated and unmethylatedCALCA gene, only percentage of lymphoblasts in peripheral blood wasassociated with methylated CALCA gene in ALL pediatric patients.Complete remission rate and mortality rate were similar in both groupsalthough those with methylated gene had a higher relapse rate. Our resultssuggest that hypermethylation of CALCA promoter may predict a higherrisk for pediatric ALL patients. However, as being a promising prognosticmarker could not be proven.