In 1978, we had the first research meeting of guanidine compound analysis in Okayama, Japan. The purpose of the meeting was to standardize the methods of analyzing guanidino compounds, because the analytic methods, even, for example, that of normal plasma, were quite different from laboratory to laboratory at that time. More than ten laboratories joined in this research project. Thereafter, the purpose of the annual meetings was extended to cover general biochemistry of guanidino compounds, and every meeting has served to promote our mutual growth and progress. The last meeting of the Japan Guanidino Compounds Research Association in 1982 brought together more than 80 members, and about 30 papers were presented there. This, the 6th annual meeting, brings the International Symposium on Guani­ dino Compounds here to Tokyo. Recently, many scientists are engaged in the research of guanidine compounds, especially in the field of clinical bio­ chemistry. I am sure that the observation of guanidinosuccinic acid in the urine of uremic patients by Dr. Cohen's research group in 1963 ignited the recent exploration of the role of guanidino compounds in renal diseases. The study of guanidino compounds does, however, have a long history. The first knowledge of guanidine was obtained by Strecker in 1861 (Annalen der Chemie und Pharmacie, 118, 151- 177, 1981).