The present study presents a simple and reliable micro-method for the semiquantitative analysis of types I and III collagen in tendons and ligaments in a rabbit model. After pretreatment of the analytical material by homogenization, a double cyanogen bromide cleavage was performed and the peptide fragments were visualized by polyacrylamide gel electrophoresis and silvcr staining. On the basis of this procedure, the method presented here can be used to analyze very small amounts of sample material (less than 10microg) by electrophoresis. The results of the study showed that type I collagen is predominant in the ligaments and the tendons of the knee, e.g., medial and lateral collateral ligaments. anterior and posterior cruciate ligaments. patellar tendon, achilles tendon, and semitendinosus tendon. However, a markedly higher proportion of type III collagen was detected in the ligaments (approximately 10%) than in the tendons (approximately 5%). The ligaments differ markedly from the tendons in biochemical mapping; the ligaments are functionally and metabolically the more active tissue and have a higher adaptation potential.