The disposition kinetics of ethylene oxide, ethylene glycol, and 2‐chloroethanol were studied following their intravenous administration to beagle dogs. Plasma concentration of ethylene oxide was found to decline exponentially with a mean rate constant of 0.024 ± 0.008 min‐1(mean ± SD) and total body clearance of 20.0 ± 5.2 ml/kg.min. Ethylene oxide was found to be metabolized mainly to ethylene glycol, which had a mean plasma half‐life of 221.0 ± 77.7 min and a total body clearance of 2.13 ± 0.58 ml/kg.min. Between 7 and 24% of intravenously administered ethylene oxide was eliminated in the urine as ethylene glycol within 24 h. The elimination half‐life and clearance values for 2‐chlorethanol were 40.8 ± 5.7 min and 10.3 ±1.7 ml/kg.min, respectively. The pharmacokinetic data gathered in the present investigation suggest that ethylene glycol rather than 2‐chloroethanol is the major metabolite of ethylene oxide in the dog.