The effect of uremia on wound healing in the rat was investigated by measuring the tensile strength of wounds and the amount of collagen formation in polyvinyl sponges implanted subcutaneously. Uremia had an adverse affect on healing capacity since there was a significant reduction in tensile strength and collagen formation in the uremic animals. Reduced healing was noted in the more severely uremic rats indicating that the degree of uremia was important. The uremic animals had a marked reduction in caloric intake and final body weight compared to control groups, and there was greater correlation between the results for tensile strength and collagen accumulation and the final body weights than the serum creatinine values. Therefore, the data suggest that nutritional factors are responsible for the demonstrated poor healing capacity associated with uremia.