Aggressive T-cell neoplasms are an infrequent complication of allogeneic organ and bone marrow transplantation. To date, chronic T-cell lymphoproliferative malignancies have not been described. The present case documents the occurrence of a T-cell large granular lymphocytic leukemia (T-LGL) in a patient following orthotopic liver transplantation. Genotype studies showed a clonal T-cell receptor beta-chain gene rearrangement. A unique feature was the detection of a specific chromosomal deletion at 1p32 involving the tal-1 gene, an abnormality previously described only in aggressive T-cell neoplasms.