The Youngkaechulgamtang(Y) is composed of four herbal drugs, including Hoelen(H), Cinnamomi Ramulus(C), Atractylodis Rhizoma Alba(A) and Glycyrrhizae Radix(G). In oriental medicine literatures, Youngkaechulgamtang is described to be effective in headache, inflammation, uremia, gastritis, diarrhea, hypertension. To estimate the clinical effectiveness of Youngkaechulgamtang, several pharmacological experiments were carried out. The results are summarized as follows: On $HgCl_2-induced$ renal failure rat, Youngkaechulgamtang showed the significant increase of $Na^+,;K^+,;Cl^-$ contents in urine and the significant decrease of creatinine and BUN concentrations in serum. Youngkaechulgamtang was more effective than mixture of 4 ingredients in the urine volume and excretion of electrolytes. In the diuretic effect, Hoelen and Atractylodis Rhizoma Alba were more effective than other drugs.