The objective of this study was to investigate the single dose and 2-week repeated dose toxicity of Aceporol 330 in ICR mice following single intravenous administration and to compare its toxicity with a commercially available solubilizer of paclitaxel, Cremophor EL. In single dose toxicity test, LD 50 of. Aceporol 330 in mice was estimated to be greater than maximum applicable dose, 4 ml/kg. However, LD 50 of Cremophor EL in male mice was determined to be 4 ml/kg. Maximum tolerated dose (MTD) of males and females in Aceporol 330-treated group and MTD of females in Cremophor EL-treated group were 3 ml/kg. MTD of males in Cremophor EL-treated group was less than 3 ml/kg. Characteristic toxic symptoms, and hematological and blood chemical changes were not observed after single dose and repeated dose of Aceporol 330 or Cremophor EL. No histopathological abnormalities were found in organs of all animal groups. Based on the linear pharmacokinetic property of paclitaxel and the higher LD 50 in mice, Aceporol 330 has a potential for use as a safer solubilizer for paclitaxel than Cremophor EL.