Twenty accessions within 11 perennial Glycine species plus soybean were tested for tolerance to 2,4-D. Soybean was severely injured by 2,4-D, but 13 of the Glycine accessions had 15% or less injury 4 weeks after 2,4-D application. Greatest 2,4-D tolerance occurred with accessions of G. latifolia and G. microphylla. There was no difference among tolerant accessions of G. latifolia and G. microphylla and susceptible accessions of G. canescens in recovery or absorption of 14C-2,4-D 1, 3, 7, or 14 days after treatment (DAT). Distribution of 14C from 14C-2,4-D in various plant parts was similar among accessions. Metabolism of 2,4-D in the tolerant accessions (81 to 89% 1 DAT) was higher and more rapid than in susceptible accessions (approximately 50%, 1 DAT). The same five metabolites plus parent 2,4-D were extracted from the treated leaf of all accessions at all sampling dates. However, relative distribution between metabolites differed between tolerant and susceptible accessions. More rapid metabolism of 2,4-D in treated leaves of tolerant Glycine accessions can explain differential 2,4-D responses.