Picked olive fruit, cv Manzanillo, in both green and half-black stages, was exposed for 1 to 2 weeks to 1-1 000 μl/l of ethylene, or dipped in ethephon at concentrations from 100 to 5 000 mg/l. All treatments inhibited anthocyanin accumulation and retarded softening of the pericarp; similar results were obtained when picked olives were exposed to a CO2-rich atmosphere. The ethylene treatments also resulted in a faster chlorophyll disappearance. These findings are discussed in relation to the role of ethylene in fruit ripening. © 1974.