The NUP98/RAP1GDS1 (NRG) is a new fusion gene, originating from the t(4;11)(q21;p15) translocation, that characterizes a subset of T-cell acute lymphoblastic leukemia (T-ALL). In this study we analyzed 43 T-ALL patients for the expression of this new molecular marker using a reverse transcription-polymerase chain reaction (RT-PCR) system, which is more sensitive and specific than cytogenetics alone, confirming that NRG-positive ALLs are infrequent, accounting for approximately 5% of cases.