The present paper deals with an aero bi call y treated tea called "Gabaron tea''. In the tea I eaves stored under anaerobic conditions, γ-arninobutyric acid (GABA) and alanine increased considerably, while glutarnic acid and aspartic acid decreased. Based on the result of 15N-glutarnic acid feeding experiment for tea leaves, it is presumed that glutarnic acid may be a source of nitrogen for the increased GABA and alanine. Ga baron tea is manufactured from green tea leaves which are stored under anaerobic conditions to increase GABA, a hypotensive compound. Although Gabaron tea has an undesirable odor, the major taste component of green tea shows small differences. When Gabaron tea is orally given to spontaneously hypertensive rats, their blood pressure decreased significantly as compared with the common green tea and the deionized water group. It is concluded that anaerobic conditions under appropriate time and temperature provide an improved tea containing a large amount of GABA with a relatively good quality. !tis estimated that an adequate firing with 110-120℃ is effective in reducing the undesirable odor of the Gabaron tea.