A t(1; 14) (p32; q11) translocation has been found by the cytogenetic study of a T cell acute lymphoblastic leukemia patient. Molecular hybridization with a probe (D14S7) which recognizes a fragment of the alpha chain T receptor gene has shown a rearranged EcoRI 11.0 kb band in addition to the germline 3 and 8 kb bands. This translocation infrequently described until now is a new example of an alpha chain gene rearrangement in T cell malignancy. Moreover the breakpoint on chromosome 1 may also involve the newly isolated protooncogene, L-myc, normally localized on the chromosomal band 1 p32.