Exposure to exogenous ethylene (C2H4) caused corolla abscission of New Guinea impatiens (Impatiens × hawkeri `Sunfire'). Abscission varied with time of exposure and C2H4 concentration. Ethylene at ≥ 1 μl·liter-1 and exposure times of 4 or more hours caused 80% to 100% corolla abscission. Simulated shipping of untreated control plants caused ≈ 65% corolla abscission. Plants pretreated with silver thiosulfate (STS) and (aminooxy)acetic acid (AOA) and subsequently exposed to simulated shipping were not different from one another, and both treatments reduced corolla abscission to ≈ 20% when applied at 1.0 mm. Plants pretreated with STS and exposed to `exogenous C2H4 showed 0% abscission, whereas plants pretreated with AOA showed no reduction in abscission when compared with control plants.