The contribution of intramuscular collagen to the tenderness of meat from chickens of different ages was investigated. Although the total collagen content of meat increased a little with advancing age, it did not correlate significantly with the tenderness of meat. The amount of the collagen rich fraction of meat decreased with advancing age, but the collagen content of this fraction increased significantly with age. The percentage of both the thermal residual collagen and the unextractable collagen increased largely with advancing age. All these results clearly show that changes in the collagen molecule affect the age-related tenderness of chicken meat greatly.