T-cell Acute Lymphoblastic Leukemia (T-ALL) is a clonal lymphoid malignancy. The present project aimed at determining the incidence of clonal TCR and junctional gene rearrangement status in Indian T-ALL patients at diagnosis and analyzing the suitability of clonal TCR and junctional gene rearrangement status at diagnosis as a prognostic marker for T-ALL. Data on increased number of patients with longer follow up demonstrated that out of thirty patients included in MCP 841 protocol and followed up for more than 5 years (average) TCR+ T-ALL (n=9) showed statistically significant increased survival (p=0.0423) compared to TCR+ T-ALL subgroup. Based on this biomarker risk-based treatment assignment may be utilized for childhood T-ALL patients. Studies re in progress to sequence TCR and junctional (CDR3) regions of T-ALL patients for variable, diversity, junctional, N region and P region bases and compare molecular expression profiles of TCR+ T-ALL and TCR+ T-ALL.