Specimens of human condylar articular cartilage, removed at necropsy, together with specimens of bovine condylar articular cartilage from commercially slaughtered cattle, were subjected to damage from cavitation (the growth and collapse of gas or vapour bubbles in a liquid) generated ultrasonically. The damaged specimens were examined using scanning electron microscopy. Pits and craters were observed on the surface of the damaged specimens which were not present on control specimens. The frequency of these features, together with the area and form factor of each feature, was noted and compared to previously published figures from anatomical studies. The results agreed well with previous studies in all parameters except frequency which was approximately one order of magnitude lower than previously published data. This suggested that cavitation was uncovering some, but not all, cell lacunae. An increase in crater frequency was displayed with age, in contrast' to a previously published decrease in lacuna frequency, which implied that adult articular cartilage becomes increasingly sensitive to damage with age. Cavitation is proposed as a possible aetiological mechanism in osteoarthritis.