Background: In a healthy skin, there is a molecularmicroenvironment that favours the survival of the melanocyte andregulates its function. In particular, keratinocytes can synthesize andsecrete several cytokines that have both stimulatory and inhibitory actionon melanocyte activity, such as bFGF and TNF-α respectively.Aim of the work: This thesis was conducted to study the role ofthe two keratinocyte- derived cytokines; basic fibroblast growth factor(bFGF) and tumour necrosis factor alpha (TNF-α ) in the pathogenesis ofvitiligo, as well as, two other hypopigmented disorders; namelyhypopigmented mycosis fungoides, and hypopigmented type of tineaversicolour.Subjects and methods: Forty eight patients, categorized into 3groups (25 vitiligo, 14 MF, 9 TV) and 10 normal healthy controls wereincluded in this study. A 4-mm punch skin biopsy was taken fromlesional skin of every patient as well as from the normal skin of eachindividual in the control group. The skin biopsy was stored as a frozensection (at -70ºC) for quantitative PCR examination of TNF-α and bFGFmRNA.Results: The level of TNF-α in lesional skin of different groupswas significantly higher than in control skin, while the level of bFGF inlesional skin of different groups was significantly lower than in controlskin. As regards the relation between these two factors, an inverse potentcorrelation of statistical significance was found in vitiligo and MF. Nocorrelation was found between these 2 factors in the TV and controlgroups.Conclusion: One important implication raised by our findings. All3 studied hypopigmented disorders (vitiligo, hypopigmented MF, andhypopigmented TV) were found to share the same change in cutaneousmicroenvironment with increased TNF-α level (a normal inhibitor ofhuman melanocyte proliferation and melanogenesis), and decreasedbFGF level (a natural mitogen for human melanocyte). Thus, this changein cutaneous microenvironment may explain the pigment loss in thesethree diseased groups as well as other hypopigmented disorders to befurther investigated.