Abstract: The invention relates to a method and a device for the contact-free determination of the mechanical rigidity of hard, as well as soft biological materials (e.g. articular cartilage) in body cavities (e.g. arthroscopically), using a defined jet of liquid. The distance between the measurement device and the measurement surface (e.g. articulation surface) is continuously measured in a predetermined measurement zone by means of an optical method. The inventive solution is suited for measuring the mechanical rigidity of native cartilage, articular cartilage substitute, cartilage deficiency fillings or of other biological materials, and therefore for the user-independent and fast analysis of the quality of regenerated materials as compared to the native starting material.