The mean lethal dose (LD50) of amygdalin in rats was found to be 880 mg/kg body weight (BW) by oral administration. However, when 600 mg/kg BW was administered orally with beta-glucosidase, all the rats died. Total and Mg ATPase activities of the heart decreased with increasing levels of administered amygdalin. When 200 mg/kg BW amygdalin was administered 2.3 mg (11.7% of the dose) was excreted intact over 48 h. Amygdalin, 7.4 mg (18.5% of the dose) was excreted when the dose was 400 mg/kg BW, while 7.5 mg (12.4% of the dose) was excreted as intact amygdalin when the dosage was increased to 600 mg/kg BW. Thiocyanate excreted within the same 48-h period was 7.0, 9.1, and 9.5 mumol representing 18, 11.2, and 7.8% of the 200, 400, and 600 mg/kg BW oral dosage, respectively. With 300 mg/kg BW amygdalin administered intraperitoneally, 4.1 mg amygdalin and 3.9 mumol thiocyanate representing 13.7 and 6.5% of the dose, respectively, was excreted. Excretion of intact amygdalin and thiocyanate was uniform when the dose was low (200 mg), but with higher doses over 70% of the excreted products were detected in the urine during the first 24 h.