Anaplastic large-cell lymphoma (ALCL) is characterized by molecular abnormalities involving ALK gene located at 2p23 which results in an overexpression of ALK. Nine different rearrangements of ALK gene have been reported; the t(2;5)(p23;q35) is the most common. The t(2;5) fuses the NPM gene at 5q35 with the ALK gene. NPM/ALK, as well as ALK activation via other molecular abnormalities, plays an important role in the pathogenesis of ALCL. The lack of tight clustering within the involved NPM and ALK genes precludes analysis using standard PCR methods. We describe a long-range nested PCR assay to detect NPM/ALK gene rearrangements.