Various field crop and vegetable seeds were exposed to possible vapors from the Na salt, an alkanolamine salt, and the methyl, ethyl, isopropyl, n-butyl, and n-amyl esters of 2,4-dichlorophen-oxyacetic acid (2,4-D) and from the isopropyl ester of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). The aliphatic (1-5 carbon) esters of 2,4-D and the isopropyl ester of 2,4,5-T are sufficiently volatile to affect adversely the germination of numerous spp. of field-crop and vegetable seeds exposed to such vapors. The degree of severity of the effect is proportional to the time of exposure. The higher aliphatic esters (4-5 carbon) of 2,4-dichlorophenoxyacetic acid are less volatile than the lower esters (1-3 carbon) as detd. by the effect of their vapors on the germination of seeds. The Na and alkanolamine salts of 2,4-D are apparently not sufficiently volatile to affect the germination of air-dry seeds. The ester vapor appears to be adsorbed on the seed coat and does not enter the dry seed before germination.