Human femoral and tibial whole bone specimens have been subjected to torsional loading at high strain rates. Torque versus angular deflection were recorded. Strain energy before fracture and torsional stiffness were calculated, and the following mean values obtained. Mean torsional stiffness for femoral bones: 562 Nm/r and for tibial bones: 101 Nm. Mean maximum torque for femoral bones: 183 Nm and for tibial bones: 101 Nm. Mean ultimate deflection: 20° for femoral bone specimens and 23°7 for tibial bone speciments. Mean energy absorption for femoral bone specimens: 35 joule and for tibial bones: 25 joule. A high variability of these mechanical parameters had been observed. It is postulated that the variation in geometry of the bone structures accounts for the variation of the mechanical behaviour of bony structures.