After oral treatment with D-penicillamine (D-Pc) or with aminoacetonitrile (AAn) for 10 days, mechanical and chemical parameters were studied simultaneously in various organs of Sprague Dawley rats. Tensile strength of skin strips and of tail tendons, breaking strength of femur bones and tensile strength of granuloma tissue (induced by implanted glass rods) were measured and calculated. In the same tissue the soluble collagen fractions and the insoluble collagen were determined. Total collagen and the ratio insoluble vs. soluble collagen were calculated. Tensile strength of skin, tendon and granuloma tissue were greatly reduced by D-Pc treatment but only minimally influenced by AAN treatment. On the other hand only AAN significantly reduced the breaking strength of bone. All these changes were closely correlated with the content of insoluble collagen in the respective tissues. The correlation coefficients to total collagen were similar but lower. The correlation coefficients between strength and the ratio insoluble vs. soluble collagen were generally still lower. Earlier findings in aged and corticoid treated rats, proving that insoluble collagen content determines mechanical strength of connnective and supporting tissue thus could be confirmed.