The basic magnetic resonance (MR) imaging pattern of normal and degenerated hyaline articular cartilage was studied in vitro in 40 fresh bovine patellae. With the use of an ample spectrum of strongly T1- to T2-weighted sequences, two zones of cartilage with different signal intensities were observed in all specimens. A superficial cartilaginous layer in the MR image with higher water content and longer T1 and T2 correlated with the tangential and transitional zones of normal articular cartilage, whereas a second MR imaging zone with shorter T1 and T2 was identified in the depth of the articular cartilage. Different functional properties in pressure resistance were observed in the two layers. In early cartilage degeneration without thinning, there was increased hydration of the superficial cartilage layer. This study suggests that strongly T1- and T2-weighted images are indispensable for evaluating details in articular cartilage degeneration.