Key words: IL-17, T cell leukemia lymphoma patients, DermatophytosisThis work aimed to:-Assess IL-17 level as proinflamtory cytokine and predictor for the outcome of inflammatory process in ATLL patients with dermatophytosis. Isolation and identification of different types of dermatophytes infecting patients with ATLL. Methodology: 58 subjects were included in this study (16 adult patients with adult T-cell leukemia / lymphomaclinically diagnosed to have dermatophytosis, 14 adult patients with adult T-cell leukemia / lymphoma clinically diagnosed to have no dermatophytosis, 12 age and sex matched patients clinically diagnosed to have dermatophytosis and 16 Age and sex matched apparently healthy Controls). Sampleswere examined microscopically using 20% KOH and cultured on into SDA containing chloramphenicol (0.5%) with/without cycloheximide (0.5%) and Dermatophyte test medium (DTM). Results: in the non-ATLL patients with dermatophytosis, the serum IL-17 level was significantly increased compared with the healthy controls. In ATLL patients either with or without dermatophytosis, the IL-17 levels were significantly lower than those in the healthy controls. There was no significant difference in the IL-17 level between ATLL patients with dermatophytosis and those without dermatophytosis. Again, it is suggested that ATLL patients have low levels of IL-17, which cannot be enhanced by the presence of dermatophytosis. Among patients with ATLL with dermatophytosis (Group I) T. rubrum was the commonest dermatophyte causing infection; 64% of samples (tineacorporis 46%, tineaunguium 18%), whereas T. mentagrophytes was the 2nd commonest dermatophyte; 27 % (tineaunguium 27%), lastly T. tonsurans; 9% (tineacorporis 9%). In patients with Non-ATLL with dermatophytosis (Group III) T. rubrum was also the commonest dermatophyte causing infection; 64% of samples (tineacorporis 7%, tineaunguium 14%, tineapedis 43%), whereas T. mentagrophytes was the 2nd commonest dermatophyte; 29 % (tineaunguium 7%, tineapedis 22%), lastly T. tonsurans; 7% (tineacorporis 7%). Conclusion: Our data provides clinical evidence linking Th17 cells to immune deficiency in ATLL and opens a new avenue in the study of tumor immunotherapy based on promoting Th17 cell population.