1. Intravenous administration of angiotensin II reduced the adrenaline content, increased the catechol-O-methyltransferase activity, and decreased the monoamine oxidase activity of rat hypothalamus. 2. Intraventricularly administrated angiotensin II reduced the noradreanline content to a smaller extent. 3. The change produced by intravenous administration of angiotensin might be indirectly caused by a response to angiotensin.