In laboratory studies with 3-amino-2,5-dichlorobenzoic acid (amiben), adsorption of 14C-amiben was less than 14C-amiben methyl ester with all adsorbents tested. Adsorption of 14C-amiben was closely associated with soil organic matter. Also, considerable adsorption of 14C-amiben and 14C-methyl ester was observed on illite clay and on Sassafras loamy sand which contains clay minerals composed primarily of illite clay. Root uptake of amiben caused more injury than shoot uptake to greenhouse-grown corn (Zea mays L., var. Nebraska 202). The relatively insoluble butoxy ethyl ester of amiben was the most toxic amiben derivative to greenhouse-grown corn. Subirrigation moved the more soluble amiben derivatives to the soil surface where they had less effect on the root system. In field studies comparing four derivatives of amiben applied preemergence to corn in 1966, best weed control was from the ammonium salt of amiben at 2 and 4 lb/A and the methyl and butoxy ethyl ester at 4 lb/A; the amide was ineffective. The ammonium salt of amiben caused early stunting of corn but did not reduce yield. Selective weed control in soybeans [Glycine max (L.) Merr., var. Clark] was obtained in 1966 with the ammonium salt, 80% wettable powder, and monomethyl amine salt of amiben at 1 1/2 lb/A, and the methyl and butoxy ethyl ester at 6 lb/A. In 1967, the best amiben derivatives for weed control in soybeans were the amide and esters. Amiben derivatives more susceptible to leaching were less effective in controlling weeds in 1967 due to excessive rainfall after amiben applications.