Five pregnant women were studied for chlorinated hydrocarbon insecticide residues in their blood and milk. Blood samples were obtained from each between 30 days of pregnancy and 115 days postpartum. Three milk samples were collected from each between three and 96 days postpartum. Sample extracts of plasma and milk were analyzed by electron-capture gas-liquid chromatography for chlorinated hydrocarbon insecticides. Eight chlorinated insecticides were detected. The concentratins of these compounds in plasma were within the lower part of the range previously reported for nonpregnant women. A small but statistically significant decrease in the plasma concentration of p,p'-DDT, p,p'-DDE, o,p'-DDE, p,p'-DDD, and total BHC was observed one to six days postpartum. The concentraion of the detected compounds in milk varied greatly among the individual women but was within the range reported by others.