Human and bovine anterior cruciate ligaments studied with the SEM demonstrate fascicular bundle and connective tissue sheath components. In the human, collagen fibers of the connective tissue sheath, although approximately the same diameter as the fascicular fibers, have an orientation suggestive of a binding rather than a tensile function. While both elements have tensile properties, it is hypothesized that the contribution from the sheath component is minimal and, consequently, detailed studies of the tensile properties of ligaments will produce meaningful data when related to the appropriate cross-sectional areas. In direct contrast to the human counterpart, the SEM appearance of bovine cruciate ligaments is tendon-like, characterized by very dense subfasciculi surrounded by very thin connective tissue sheaths.