Present inquisition deals with distribution of BuchE in the developing rat brain. In all the age groups under study, enzyme activity appeared particularly in the blood vessels. Some nuclei showed activity in blood vessels only, while others demonstrated activity in both vessels and neuropil. At birth (0days-old) activity was very weak in blood vessels as well as in neuropil. With the age advancement, in enzyme activity increased. At adult stage (90 days-old) certain blood vessels and neuropil areas demonstrated very intense activity in comparison to areas with light activity for the enzyme. Study not only incorporates topographical survey of BuchE distribution in medulla but functional significance in relation to blood brain barrier and differentiation of nuclei have also been discussed.