T cell receptor TCR γ gene rearrangement in a series of acute lymphocytic leukemia (ALL) patients was studied using PCR technique. 18 V-J junctional sequences (designated by N sequence) of TCR γ gene were amplified with the Vγ and Jγ primers, using an unsymmetrical PCR and analysed by direct sequencing, demonstrating that in Chinese ALLs, the N sequences of TCR Y gene are indeed clone-specific. Based on the known N sequences, several oligo-nucleotides were sythesized as probes, which were specific for the leukemic clone, and were used to detect the minimal residual disease (MRD) in 4 ALL cases. The sensitivity of this method was 0.1%-0.01%. T cell receptor TCR γ gene rearrangement in a series of acute lymphocytic leukemia (ALL) patients was studied using PCR technique. 18 VJ junctional sequences (designated by N sequence) of TCR γ gene were amplified with the Vγ and Jγ primers, using an unsymmetrical Based on the known N sequences, several oligo-nucleotides were sythesized as probes And were used to detect the minimal residual disease (MRD) in 4 ALL cases. The sensitivity of this method was 0.1%-0.01%.