The application of ultrasound backscatter microscopy (UBM) to elucidate the structure of articular cartilage in vitro has been investigated. Imaging was performed at 50 MHz with axial and lateral resolution of 30 μm and 60 μm respectively. All parts scanned except the weight bearing regions of the femoral condyles demonstrated heterogeneous ultrasound backscatter characteristics within the cartilage. Microscopic details such as varying thickness of cartilage, changes in the relative thickness of each of the cartilage layers, disruption of the subchondral bone plate, and presence of perichondrium on the articular surface were detected with UBM. Correlation with histological finding will be presented and potential application to cartilage imaging in vivo will be discussed.