A rigorously designed auxological study was carried out to assess the operational characteristics of the knemometer and the value of short term lower leg and height measurements in estimating and predicting rates of linear growth. Measurements were made on 18 normal children monthly for six months and on six normal children weekly for six weeks. Six other children measured weekly underwent tonsillectomy after three weeks to determine the effect of stress on growth. The measurement protocol permitted estimations of both inter- and intraobserver variation. Knemometry is a sensitive, precise, and robust technique that enables accurate measurements to be made of the lower leg by interchangeable observers. The lower leg does not grow smoothly and variations in growth rate seen in both healthy children and children with transient intercurrent stress limit the practical clinical value of knemometry to the measurement of linear growth in the short term.