The volatile flavor compounds of two transgenic tomato fruit (Lycopersicon esculentum Mill. cv. Ailsa Craig), transformed with either an ACC-oxidase (ACO1) antisense gene construct or a polygalacturonase (PG) sense suppression gene construct, were analyzed at various stages of tomato fruit ripening compared to non-transformed fruit. Nine key volatile flavor compounds released following maceration of the tomato tissue were measured, using Atmospheric Pressure Chemical Ionization-Mass Spectrometry (APCI-MS) in real-time analysis. ACO1 antisense fruits, which showed less activity of ethylene production, had lower levels of most volatiles measured throughout ripening compared to wild type and PG sense suppression fruits. PG sense suppression fruits, with low polygalacturonase activity, would be expected to have the same quality as wild-type fruits in terms of volatile components.