Insulin administration rectally with the liposome has the hypoglycemic effect in the rabbits. The reducton in blood sugar was maximum at about 60 minutes after administration and continued for 4 hrs. at low level in these experiments. No hypoglycemic effect was observed in control administrated rectally without liposome. Rectal absorption of insulin has been effected by addition of the bile salt, as the protective agent which prevented denaturation and the phastransition of insulin in liposome-encapsulation. As a matter of the fact, a significant hypoglycemic action was obtained when the insulin-liposome was given by rectal administration. The use of this agent to enhance insulin absorption offers the possibility of a new approach to rectal insulin therapy.