Downy mildew (Plasmopara viticola) and anthracnose (Sphaceloma ampelinum) are two of the major diseases of most grapevine (Vitis vinifera L.) cultivars grown in Thailand. Therefore, breeding grapevines for improved downy mildew and anthracnose resistance is crucial. Factorial crosses were made between three downy mildew and/or anthracnose resistant lines (‘NY88.0517.01’, ‘NY65.0550.04’, and ‘NY65.0551.05’; male parents) and two or three susceptible cultivars of V. vinifera (‘Black Queen’, ‘Carolina Black Rose’, and/or ‘Italia’; female parents). F1 hybrid seedlings were evaluated for downy mildew and anthracnose resistance using a detached/excised leaf assay. For both diseases, the general combining ability (GCA) variance among male parents was significant, while the ariance of GCA among females and the specific combining ability (SCA) variance were not significant, indicating the prevalence of additive over non-additive gene actions. The estimated narrow senseheritabilities of downy mildew and anthracnose resistance were 55.6and 79.2%, respectively, suggesting that downy mildew/anthracnoseresistance gene(s) were highly heritable. The ‘Carolina Black Rose xNY65.0550.04’ cross combination is recommended for future use.