LC50 of 2-bromopropane was reexamined by using the OECD guideline in ICR mouse. The mice, 3 males and 3 females, were exposed to 2-bromopropane at five different concentrations for 4 h in inhalation chambers. The exposed animals were observed for 14 days. The animals which had survived and died were counted for the LC50 determination. The LC50 was calculated by using a dose-mortality curve at a 95 percent confidence level. The LC50 was 31,171 ppm, and the lowest lethal concentration (LLC) was lower than 29,528 ppm and the lethal concentration at 100% (LC100) was higher than 32,905 ppm.