Polymerase chain reaction (PCR)-based amplification of T-cell receptor (TCR)-γ genes is a novel technique that can detect a clone of T cells comprising less than 1% of the total T cells in a lymphoid infiltrate1. Besides greater sensitivity than Southern blotting, this technique can be performed with smaller quantities of lower molecular weight genomic DNA as template. We retrospectively analyzed 12 paraffin-embedded biopsies of cutaneous T-cell lymphoma (CTCL), 1 case suspicious for CTCL, 1 case of granulomatous slack skin, and 8 cases of inflammatory skin diseases to determine if PCR-denaturing gradient gel electrophoresis (PCR-DGGE) analysis can detect TCR-γ gene rearrangements on paraffin-embedded specimens. We were able to amplify Vγ1-8 TCR sequences in each case and detected a dominant clone in 9 of 12 cases of CTCL and in granulomatous slack skin. We analyzed Vγ9 sequences in 9 cases of CTCL and detected a dominant clone in 4 cases. This study demonstrates that PCR-DGGE can easily be applied retrospectively to cutaneous biopsies of lymphoproliferative diseases when fresh tissue is not available.