The present study directed in two successive seasons of 2006 and 2007 to assess some of compatibility parameters measured between four commercial Grape cultivars grafted onto Harmony rootstock ; percentage of grafting success, vigor of grafts, lignin content of cell wall at union zone and NPK content of leaf petioles. An apparent increase in values of these characteristics that may be considered as good indicators to the compatibility between Superior cultivar onto Harmony rootstock, Superior surpassed the other grape cultivars and showed more compatibility. Thompson seedless and Flame seedless onto Harmony were intermediate in this respect. However, King Ruby cultivar onto Harmony showed less compatibility. King Ruby/Harmony was the highest in NPK content % in its leaf petioles than other cultivars tested in this study during the two seasons. Moreover, Thompson seedless/Harmony gave significant response in leaf surface area / No. of leaves / shoot, fresh and dry weight/leaves/shoot of graft combinations followed by Superior/Harmony, Flame seedless/Harmony and King Ruby/Harmony during both seasons of study. In addition, both Flame seedless and King Ruby onto Harmony rootstock gave the highest values of lignin content % in union zone.