Abstract: A sealing boot for sealing a power transmitting mechanical joint, especially a mechanical joint which is subject to angular articulation between its input shaft and output shaft. The mechanical joint has an outer race which is a part of its output shaft, and the outer race has an external spherical surface. The sealing boot has a non-flexible portion which surrounds a portion of the outer race, and this non-flexible portion has a spherical inner surface which sealingly engages the external spherical sealing surface of the outer race in surface-to-surface contact. The non-flexible portion of the boot and the outer race of the joint can be articulated relative to one another without breaking the seal therebetween. In the preferred embodiment the remainder of the boot constitutes a non-pleated non-flexible second boot segment, one end of which is received in a spherical slot of the first non-flexible portion and the other end of which sealingly engages the input shaft of the mechanical joint.