Ripening is the main physiological process that affects the behaviour of fruit quality traits. The progress of this process in banana fruit is different for fruit ripen or not on the tree and according to the treatment applied to the fruit after harvest. We investigated the effect of the mode of ripening on ethylene biosynthesis of IDN 110 (M. acuminata, AA) banana fruit ripen in-planta (in-Fruit) and ex-plant on air (air-Fruit) or after acetylene treatment (ace-Fruit). The levels of ACC and ethylene production and, those of ACC oxidase (MA-ACO1 and MA-ACO2) and ACC Synthase (MA-ACS1) mRNA were examined in pulp tissue of each of these fruits. Our results showed that, from the harvesting point made at mature-green stage, the ripening speed of fruit was not correlated with ethylene production. Ace-Fruit took 10 days to reach over-ripe stage with a maximum of 22.6 ^l.kg-1.h-1 of ethylene production, whereas Air- and in-Fruit took 27 and 33 days to reach over-ripe stage, respectively, and produced 11.5 and 29.6 ^l.kg-1.h-1 of ethylene, respectively. During ripening, ACC accumulated differentially and, except for in-Fruit, this accumulation was positively correlated with that of MA-ACS1 mRNA. No correlation was observed between ACC level and ethylene production. In all cases, the level of MA-ACO1 mRNA was 100-fold more than that of MA-ACO2, and both of them increased during fruit ripening. In contrast to MA-ACO2, the pattern of MA-ACO1 gene expression was correlated with that of ethylene production whatever the mode of ripening. The results herein suggested that i) the level of ethylene is not the nique factor that controls the speed of fruit ripening in-planta, ii) the level of ripening-ethylene production of the whole fruit is regulated at downstream step of ACC biosynthesis mediated by MA-ACS1 gene and, in pulp tissue, the product of MA-ACO2 might be involved in this regulation.