Three major radioactive compounds have been found in 80% alcohol extracts of bean stems from plants treated with either α-methylene or carboxyl C 14-labeled 2,4-D. One of the compounds was identified as 2,4-D. The R f values of these compounds were respectively: 0.76 – 0.78 and 0.83 – 0.86 for 2,4-D, 0.55 – 0.59 and 0.29 – 0.32 for unknown 1, and 0.32 – 0.35 and 0.66 – 0.73 for unknown 2 when chromatographs containing the extracts were developed with phenol saturated with water and butanol-propionic acid-water. Free 2,4-D and unknown 1 were also found in the 80% alcohol extracts of leaves from bean plants treated with α-methylene C 14-labeled 2,4-D. The concentration of 2,4-D in the stem extracts decreases to a minimum and then rises at a later date. A corresponding increase occurs in the concentration of unknown 1. A drop in its concentration occurs at the time the concentration of 2,4-D begins to increase. A similar relationship is observed in the leaf extracts. The close relationship between unknown 1 and 2,4-D, as well as the large quantity of unknown 1 formed, and the relatively great stability of unknown 1, suggests that a detoxification reaction may be operative in the plant. Unknown 1 may be a glycoside containing 2,4-D as the aglycon group.