Abstract: Acetylcholine, histamine and dermographism were tested on the skin of some dermatoses with different inflammation base, the abnormal responses were prominent over skin lesion and normal appearing skin of the patients with atopic dermatitis (AD), they were not specific but were of help for the diagnosis. Analysis on the subsets of AD and different parts of the skin tested showed.ahat the abnormal responses in addition to the secondary effect of the inflammation were related to the atopic diathesis as well.