Serotonin was chemically identified as 5-hydrowytryptamin which occurs in plants, animals, and human beings. The end product of metabolism was excreted as 5-HIAA in urine. Many scientists, specially biochemist and psychiatrist reported that the change of serotonin concentration caused mental disorder and pathological condiions such as schizophrenia and carcinoid. This study was carried out to observe the urinary 5-HIAA excretion rates changed by three recipes treatment (Kamisoyosan, Ondamtang, kalgunhaegitang) according to the classification of endogenous, exogenous and non-exo-endogenous, causes of disease. The urinary 5-HIAA excretion rates before and after three recipes treatment on normal groups divided into three groups on the basis of physical constitutional differences and on patients groups, divided into three groups according to the causal factor were measured. The results were as follows; 1. The urinary 5-HIAA volume of patients groups appeared non-exoendogenous, endogenous, exogenous causes of disease in order of three causative classification. 2. The urinary 5-HIAA volume of Normal groups was $2.50{pm}088mg/24hrs$(range $0.30{sim}6.90mg/24hrs$) 3. Thr urinary 5-HIAA volume was $3.70{pm}0.89mg/24hrs$(range $0.90{sim}6.50mg/24hrs$) before kamisoyosan treatment and $3.20{pm}0.72mg/24hrs$ (range $0.80{sim}6.20mg/24hrs$) after the treatment. 4. The value was $2.60{pm}0.10mg/24hrs$ (range $0.60{sim}6.50mg/24hrs$) before Ondamtange treatment and $2.00{pm}0.12mg/24hrs$(range $0.20{sim}6.10mg/24hrs$) after the treatment. 5. The value was $4.30{pm}0.75mg/24hrs$(range $0.92{sim}6.50mg/24hrs$) before kalgunhaegitang treatment and $3.10{pm}0.10mg/24hrs$(range $0.80{sim}5.80mg/24hrs$) after the treatment. Considering the above-mentioned the study on the changes of urinary 5-HIAA volume will make a significant contribution to the diagnosis and the evaluation of therapeutic effect successive research and modified application will be in need.