Summary1. The acute toxicity of 2-ethyl hexanol following intraperitoneal injection in 101 rats has been measured. The LD 50 was found to be of the order of 0.08 cc per 100 g rat. From the administration of 2-ethyl hexanol by stomach tube to 85 rats, the LD 50 has been shown to be of the order of 0.39 cc per 100 g rat.2. A marked anesthetic quality of 2-ethyl hexanol was observed.3. 2-ethyl hexyl phthalate given by stomach tube to 50 rats in doses of 1 to 34 g per kg body weight produced no deaths. 2-ethyl hexyl phthalate has a very low order of toxicity in rats.4. 2-ethyl hexyl phthalate given intraperitoneally in doses of 1, 2, and 3 cc respectively, to 65 mice resulted in the death of 7. However, only one mouse in a group of 20 was killed by the largest dose (128 g per kg body weight). 2-ethyl hexyl phthalate has a very low order of toxicity in mice.