Objective To assess the diagnostic significance of T cell receptor gamma gene rearrangemerits in mycosis fungoides (MF), so as to develop a sensitive diagnosis tool. Methods A total of 50 specimens were collected, including 33 skin lesion specimens and 2 lymph specimens from 30 patients with MF,15 skin lesion specimens from 15 patients with inflammatory dermatoses. PCR was performed with specific primers targeting TCR V gamma 8, 9, 10, 11 to detect T cell receptor gamma gene rearrangement. Results Monoclonai rearrangements of TCR gene was observed in 88% (29/33) of specimens from patients with MF and 33% (5/15) of samples from patients with inflammatory dermatoses. Conclusions The detection of TCR gene rearrangements, as an ancillary test, is useful in the diagnosis and differential diagnosis of MF.