The aim of this study was to determine the tensile strength and the elasticity of the tunica albuginea (TA), and describe morphological structures in the tissue before and after mechanical deformities. Twenty cadavers of men aged between 33 and 83 were examined. Cavernosometry was performed in all specimens. Afterwards in five cadavers the flow rate was increased until a herniation of the TA appeared. A strength about 1500 mm. Hg was found. Similar results were found in four who had an inflatable prosthesis (AMS 700) inserted, and the intraprosthetic pressure increased until a deformity was noted. Slices of TA (thickness 1.3 to 3.3 mm.) from 11 specimens were tested in a tensiometer. The elasticity coefficient was found to be around 10(8) N/m2, and the tensile strength to be 600 to 750 mm. Hg (10(4) to 10(5) N/m2). The difference between the tensile strength achieved in the tensiometer and during saline infusion is possibly caused by the intracavernous framework. Microscopy showed that TA is mainly composed of collagen fibres which are situated in an undulating arrangement, with a few elastic fibres arranged longitudinally which connect the undulating bundles of collagen fibres. When the tissue is overstretched, the elastic fibres are destroyed and the undulating arrangement disappears.