Pregnant mice were exposed to 500ppm of monochlorobenzene, 500ppm of trichloroethylene and 1000ppm of 1, 1, 1-trichloroethane for 1 hour. The transfer of each solvent to the fetus through the placenta was investigated by gas chromatographic equilibration. The distribution of solvents among organs of the mother was also investigated. Monochlorobenzene just after exposure was in the desending order of concentrations in the adipose tissue, liver, kidneys and brain of mothers. This order was the same as that of non-pregnant mice. It was shown that these three organic solvents transferred from the mother to the fetus. Concentrations of monochlorobenzene and trichloroethylene were higher in the placenta than in the blood. The concentration of 1, 1, 1-trichloroethane was slightly lower in the placenta than in the blood. The ratio of transfer of these three organic solvents from the placenta to fetuses was about 1/3. The transferability to the placenta and fetuses, and to the liver, kidneys and brain, of monochlorobenzene was higher than that of trichloroethylene.