Turimycin is characterised by low acute toxicity. Mean lethal doses for mouse and rat are 750 mg/kg body weight for intraperitoneal application of something in excess of 3,000 mg/kg for oral administration. The blood pressure of anaesthetised cats may be reduced by amounts depending on intravenous Turimycin doses (between 10 and 50 mg/kg). The hypotensive effect of Turimycin is attributable to its negative inotropic effect on the heart and its spasmolytic action on the unstriated muscles. Reversible reduction of urine and ion excretion of rat following intraperitoneal application of 50 mg/kg body weight of Turimycin is interpreted as a consequence of such action upon blood pressure. A preliminary study was conducted into dogs which had orally received daily Turimycin doses of 50 or 125 mg/kg body weight over twelve months. No substance-depending functional or morphological damage was recorded.