The results are recorded of a number of studies performed over the last few years using a simple and reproducible method for investigating the extensibility of intact skin. A major advantage of this method lies in the fact that it causes the patient no discomfort and leaves his skin without blemish. We have found abnormal behaviour of skin in response to applied stress in the heritable connective tissue disorders: Ehlers-Danlos Syndrome, cutis laxa, and pseudoxanthoma elasticum, and in the acquired disorders of acromegaly, hypopituitarism and scleroderma. An abnormal elastic modulus, however, was found only in pseudoxanthoma elasticum and the growth-hormone disorders.