This paper deals with the investigation of the cholesterol and lecithin content of whole blood in a miscellaneous group of skin diseases : acne vulgaris, alopecia areata, alopecia cicatrizata, Bazin's disease, chloasma, neurodermatitis, occupational dermatitis, seborrheic dermatitis, dermatitis venenata, dermatophytosis with general and localized involvements, chronic eczema, furunculosis, herpes zoster, keloid, lichen planus, lipoma, lupus erythematosus, onychomycosis of the hands, pityriasis rosea, prurigo nodularis, psoriasis, purpura simplex, sarcoid, tinea capitis and versicolor, urticaria, von Recklinghausen's disease and xanthoma. Our object in undertaking this work was primarily to ascertain whether there are variations in the blood lipids in these diseases. An accumulation of such data may be helpful in discovering the still doubtful etiology of certain of these dermatoses, in alleviating the symptoms and, perhaps, in finally attaining proper therapeusis. This is an immense program. Hence, the study to be detailed presently cannot be considered more than an introduction although