Intact caryopses of dormant AN265 and M73 wild oat (Avena fatua L.) lines did not germinate when imbibed in water at 14°C, but germinated after exposure to ethylene during imbibition. Embryos excised from dormant caryopses and imbibed in water germinated readily. However, inhibitors of ethylene synthesis ([aminooxy]acetic acid and 2-[aminoethoxyvinyl] glycine) and ethylene action (2,5-norbornadiene and silver thiosulfate) delayed or almost completely inhibited germination of excised embryos. Embryos removed from inhibitor treatments after 15 d and incubated in water germinated normally. Except for 2,5-norbornadiene, inhibitors did not reduce germination of intact nondormant (afterripened) caryopses or embryos excised from nondormant caryopses. Reduced germination rates of embryos excised from dormant caryopses and incubated in 2,5-norbornadiene and 2-(aminoethoxyvinyl) glycine were reversed by applications of 0.05 μL/L ethylene. The results indicate that wound-induced ethylene synthesis may be responsible for germination of embryos excised from dormant wild oat caryopses.