Articular cartilage provides joints with excellent lubrication, wearing characteristics and a smooth efficient weight-bearing system. Swelling of articular cartilage serves as an important biomechanical property and one of the early signs of osteoarthritis (OA). The aims of this study were to build a high-frequency ultrasound system and to investigate the transient osmosis-induced free shrinkage-swelling behavior of articular cartilage in a non-destructive and non-contact way. Cylindrical cartilage-bone specimens were prepared from the normal mature bovine patellae. The transient shrinkage (de-swelling) and swelling behaviors of cartilage were induced by changing the concentration of the bathing saline from 0.15 M to 2 M and then back to 0.15 M. The shrinkage and swelling phases were monitored and quantified using ultrasound. It was found that both shrinkage and swelling responses showed 'overshoot-relaxation' phenomena. The absolute value of the peak shrinkage strain (0.75% ± 0.57%) was significantly larger than the peak swelling strain (0.28% ± 0.28%) (p 0.98) and a good reproducibility (relative error