SummaryThe effect of local temperature an the transference of protein mid of the lipoproteins from plasma to lymph in the hind paw of hypercholesterolaemic rabbits has been studied before and after thermally injuring the paw by immersion in water at 60° for 1 min.The hind paws were kept either at 10° or 45°. In uninjured limbs the lymph flow was greater, but the concentrations of albumin, globulin, total cholesterol and phospholipid were less with the paw at 45° than at 10°.After injury to both paws, the lymph flow and also the concentrations of albumin and of the lipoproteins of densities 1·063–1·200, 1·019–1·063 and<1·019 g./ml. were greater with the paw at 45° than at 10°, but in each case molecular sieving of these macromolecules was evident, although at a different level. These results suggest that, after a thermal injury, the sieving mechanism of the skin capilliries can be varied by altering the capillary pressure.