The present study was undertaken to investigate effects of Perillae Folium juice on the respiration and blood pressure in cats. Also studied was the mechanism of depressor action of PFJ. The results obtained are as follows; 1) Following administration of 0.2 ml/kg, 0.4 ml/kg and 0.6 ml/kg PFJ into cats the maximum depressor responses observed were 48.5+3.6 mmHg, 56.8+4.3 mmHg and 71.1+2.9 mmHg respectively. 2) Depressor responses to PFJ were blocked makedly by atropine and partially by propranolol. Therefore it is strongly suggested that depressor action of PFJ results mainly from cholinergic effect and partly from activity of β-receptor. 3) After administration of PFJ into cats tachypnea preceded by a short period of apnea was observed invariably.