The axial deformation behaviour of arterial walls and their anisotropy were studied experimentally using abdominal aortas, common carotid arteries and femoral arteries obtained from mongrel dogs. These tubular specimens were stretched in the axial direction keeping the internal pressure at various levels. Main results obtained were: the strain rate dependency of axial mechanical behaviour is not observed in the range of 3×10−3 to 3×10−1 per second; mechanical properties of arteries in the axial direction are dependent on the internal pressure applied; in the lower stress range, arterial walls are more extensible in the circumferential direction than in the axial direction, and an apposite trend occurs in the higher stress range; mechanical properties of arterial walls in the axial direction are expressed by the constitutive equations that we proposed in a previous paper.