It has been reported that mechanical properties of tissue-engineered cartilage were significantly lower than those of natural cartilage, even though many efforts have been made to regenerate high quality articular cartilage by tissue engineering techniques. Further studies must be conducted to find an optimal technique for regeneration of qualitative cartilage with the type of cells, extracellular matrices, growth factors, scaffolds, and bioreactors providing a proper mechanical stimulation. In this study, the effects of culture time and three different kinds of extra cellular matrixes (ECM) in two levels of density on the variation of stiffness (Young's modulus, E) of chondrocyte were evaluated by the cytoindentation technique. Compared with no ECM coating, all kinds of ECM coatings improved Young's modulus of chondrocyte. Type 11 collagen and fibronectin significantly increased the Young's modulus of chondrocyte after 4 h culture time. This suggested that the variations of biological environment affected the biomechanical property of chondrocyte. This result provided the valuable information to tissue engineering approaches for obtaining more improved biomechanical property of regenerated cartilage tissue. (c) 2005 Elsevier B.V. All rights reserved.