Parathion was detected in young bean leaflets 2 hours following application to soil of plants grown in sterile root culture. Studies of accumulation of parathion within the plant during 24 hours following soil application indicated that uptake continued during this period, but slowed considerably after 6 hours. Results of analysis for parathion degradation products from tissue extracts indicated that most, if not all, the parathion molecule remained intact within the plant after more than 22 hours. Higher concentrations of parathion occurred at left margins than in the central portions of the leaf blade. The Insecticide appeared to be transported selectively by certain leaflet veins. Younger leaflets accumulated higher concentrations than did older leaflets over the same time period. Parathion was not detected in root exudates 24 hours following foliar application. Several species of sucking insects apparently fed but did not die after being exposed to leaves for 24 hours following soil application. In 1 test low levels of parathion or parathion-associated metabolites were detected from insects after 24 hours exposure.