Botrytis cinerea and Penicillium expansum are the most important pathogens of apples during the postharvest phase. In the present study, the effect of ozone (O-3) and carbon dioxide (CO2) gases combined with application of the yeast isolates Candida membranifaciens A2, Saccharomyces cerevisiae 69, Pichia guilliermondii M47 and A6, was investigated to control blue and gray molds of apples in vitro and in vivo conditions. In vitro, O-3 and CO2 treatments exerted respectively fungistatic and fungicidal activity on fungal spores. In dual culture tests, the combination of antagonistic yeasts with CO2 was the most efficient way to control the growth of both pathogens. In vitro, O-3 completely inhibited the growth of yeast isolates, whereas CO2 did not influence the yeast growth. Inoculation of apples with C. membranifaciens A2, P. guilliermondii A6 or S. cerevisiae PTCC 69 in combination with CO2 completely suppressed blue or gray mold symptoms for up to 62 days of storage, both at 20 degrees C and 4 degrees C. Yeasts combined with O-3 (10 ppm) were poorly effective in controlling disease development on fruit. However, CO2 or O-3 treatments used alone resulted in a decrease of apple quality after 62 days of storage at 4 degrees C; necrotic spots were observed for fruits treated with O-3.