A method of recording bone strain in the walking animal has been described (Cochran 1969). This communication describes a method of application of train gauges directly to bone which gave dependable and reproducible results. A telemetry system designed and built for the purpose of transmitting strain patterns from the walking animal is described. This has eliminated the need for long trailing wires from the animal, and has noise free recordings which can be made from six strain gauges simultaneously. The techniques and instrument described will be used to investigate in vivo the normal deformation of bone and the effect of various internal fixation devices on this deformation.