Incorporating biotin-11-dUTP, the rearranged fragment Vδ2-Dδ3 of T cell receptor gene has been amplified by nest PCR from bone marrow DNA of acute lymphoblastic leukemic patients to get biotin-labeled leukemic clonospecific probe for detection of minimal leukemic cells. The initial results of dot hybridization show that the clonospecific probes are sensitive and specific for identifying residual leukemic clone in clinical practice.