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Exogenous application of ABA (abscisic acid) to intact miniature potted rose plants (Rosa hybrida L.) resulted in deterioration of postharvest quality of two cultivars. Spraying with ABA increased leaf drop and accelerated flower senescence in ‘Vanilla’ and ‘Bronze’, while bud drop was only induced in ‘Bronze’. Application of ABA to detached rose flowers accelerated their senescence, indicating that the observed senescence promoting effect was not a secondary response resulting from ABA-induced leaf senescence and abscission. ABA-treatment increased ethylene production in ‘Bronze’ flowers, while no ethylene production was measured in flowers of ‘Vanilla’, or in the leaves of both cultivars. Pre-treatment with 1-MCP (1-methylcyclopropene) delayed ABA promoted flower senescence in ‘Bronze’, suggesting that the effect of ABA is at least partly mediated by ethylene. The senescence promoting effect of ABA on leaf drop and flower life of ‘Vanilla’ flowers was not counteracted by 1-MCP pre-treatment. The cultivar ‘Vanilla’ had a low ABA level at all flower stages, while ABA content of the ‘Bronze’ petals was high in buds, lower in open flowers, and increased during flower senescence. An increased ABA content after ethylene treatment in ‘Vanilla’ suggests that ethylene, natural or exogenous, can increase ABA levels of flowers.