We investigated the effects of Shakuyaku−kanzo−toh a long term orally taking on bodyweight, blood pressure and electrolytes（Na＋, K＋, Cl−）in rats. Shakuyaku−kanzo−toh did notaffects on body weights, blood pressure in rats at normal and 30 times higher doses. Serumelectrolytes K＋ significantly decreased both normal dose and 30 times higher dose of Shakuyaku−kanzo−toh. Treatment of Aspara K did not recover the decrease of serum electrolytesK＋. Our results suggested that Shakuyaku−kanzo−toh is safety medicine. However, itis important when administration of Shakuyaku−kanzo−toh should be carefully to check constitutionsof each patients.（Jpn Pharmacol Ther 2009；37：657−61）KEY WORDS Shakuyaku−kanzo−toh, Pseudoaldosteronism, Hypertension