This investigation involves an evaluation of the effects of subzero temperatures on the cellular viability of human costal cartilage. Cellular viability was determined on cartilage frozen at –20 C and in liquid nitrogen, with and without the use of the protective additives glycerol and PVP (polyvinylpyrrolidone). It has been found that these additives brought about a significant decrease in the cellular survival of human cartilage at 3 C, suggesting an inherent toxicity of the additives and indicating an increase in toxicity with increasing concentration of the agent. Fifteen percent glycerol-saline, 3.5% PVP, 7.5% PVP offer no protection, possibly due to high toxicity. None of the additives afforded any cellular protection during freezing in liquid nitrogen. A profound disruption in cartilage metabolism was indicated after freezing at –20 C both with and without a protective medium.