Hemorrhagic shock was produced by bleeding conscious rats to a mean arterial pressure of 40 mm Hg, which was maintained for 2 hr. Basal glucose uptake by isolated soleus muscle from normal rats and rats subjected to hemorrhagic shock ('shock' muscles) increased with the increase in medium glucose concentration. Uptake values were similar in both groups of muscles. This indicates that there were no alterations in the basal glucose carrier mechanism during shock. Whereas insulin (0.1 U/ml) stimulated glucose uptake in control muscles under aerobic as well as under anaerobic conditions, it had no stimulatory effect in 'shock' muscles under either environment. Maximal stimulation of glucose uptake in 'shock' muscles was observed at an insulin concentration of 0.2 U/ml. The ability of muscle to bind insulin was not altered during shock. The present experiments indicate that insulin responsiveness to tissues is altered in shock. This could be due to alterations in the insulin sensitivity of the glucose carrier mechanism during shock.