The human cutaneous basement membrane (CBM) has been isolated together with the anchoring fibrils (AF) of the dermis. These structures are removed from the dermis as a single complex, the CBM-AF complex. The epidermis is first removed from the dermis by immersion of whole, defatted skin in cold 2 n NaSCN for 5 to 6 hr. Subsequently, removal of the CBM-AF complex is effected by focusing high-intensity ultrasonic energy against the dermal surface. Purification of the preparation is achieved by low-speed sedimentation. All stages of the process were monitored by electron microscopy, which demonstrated that the morphology of the CBM-AF complex was well preserved and that this complex represents the principal mass component in the system. In addition, our report describes an ultrasound-induced variation in collagen fibril morphology, which we have called 'disordered collagen.' This altered type of fibril lacks periodicity or recognizable banding and has a frayed appearance. Finally, the experiments provide the basis for an analysis of the relative strengths of certain bonds at the dermal--epidermal junction. The strongest of these appears to be the bond between basement membrane and anchoring fibril.