Background: As the standard clinically used hypotensive medicines have many undesirable side effects, there is a need for new therapeutic agents, especially ones of a natural origin. Purpose: One possible candidate is extract from the mushroom Reishi (Ganoderma lucidum), which is used in the treatment and prevention of many chronic diseases. Study design and methods: To study the effectiveness of Reishi, which grows in the Altai Mountains, as an antihypertensive agent, we intragastrically administered Reishi water extract to adult male hypertensive ISIAH (inherited stress-induced arterial hypertension) rats. Results: After seven weeks, Reishi therapy reduced blood pressure in experimental animals at a level comparable to that of losartan. Unlike losartan, intragastric Reishi introduction significantly increases cerebral blood flow and affects cerebral cortex metabolic patterns, shifting the balance of inhibitory and excitatory neurotransmitters toward excitation. Conclusion: Changes in cerebral blood flow and ratios of neurometabolites suggests Reishi has a potential nootropic effect.