Treatment with 1-methylcyclopropene (1-MCP), a potent inhibitor of ethylene action, delayed the decrease in fruit firmness and the time in peaks of respiration and ethylene production rates, 1-aminocyclopropane-1-carboxylic acid (ACC) concentration, and ACC oxidase (ACO) activity of banana fruit, but exogenous ethylene treatment was not able to induce fruit ripening when the fruit was treated with 200 nL/L of 1 MCP. Furthermore, 1-MCP treatment delayed expression of ACC synthase (ACS) and ACO genes, two ripening- related genes in ethylene synthesis. These results demonstrated that ripening process of banana fruit was delayed at a physiological level by 1-MCP, while ethylene synthesis could be regulated at suppressed transcript levels of ACS and ACO genes.