Proteins isolated in quantity from porcine lung and stomach have been modified into fibrous forms. Stable dispersions could be prepared from the isolates on alkali treatment, the final viscosity depending upon protein and alkali concentration and the pH of isolation. Fibrous products spun from these protein sources appear to have lower elasticity than those spun from concentrated blood plasma. The spinning of admixtures of lung and stomach proteins with plasma gave rise to poor mechanical properties in the resultant fibres. However, amino acid analysis has indicated that such procedures effectively supplement isoleucine and methionine, deficient in spun plasma products.