Cytokines play an important role in both physiology and pathophysiology of human skin, and the possibility that they coordinate the cyclical hair growth cannot be excluded, Several clinical and experimental data point towards interleukin-1 which might be a crucial inducer of hair loss in various hair diseases, An aberrant expression of interleukin-1 beta was detected in affected areas of the scalp in alopecia areata. On the other hand, interleukin-1 has been shown to be a potent inhibitor of human hair growth in vitro, Mice showing an overexpression of the interleukin-la gene develop patchy hair loss. Taking all of the presently available data together, We hypothesize that interleukin-1 is a crucial mediator inducing cessation of hair growth.