This experiment was carried out during the two successive seasons of 2003 and 2004 to study the eflect of foliar application of mineral or chelated calcium and magnesium on fruit quality and keeping quality during storage at room temperature of Thompson Seedless grapevines. grown in a sandy soil under drip irrigation system at El - Sadat region. Menoufeya Govemoratex'Fhe vines were quadrilateral cordon shaped and trellised by the Spanish Parron system. Ten years old Thompson Seedless grapevines received three foliar sprays In each season. i. e. at the beginning of vegetative growth (2"“1I week of March). immediately after fruit set (1" week of May) and 4 weeks later (1" week of June). The tested foliar spray treatments included control (water spray). Ca CI; at 0.5%. 1% and 2%. Ca - EDTA at 0.1 %. 0.2% and 0.3%. Mg 804 at 0.5%. 1% and 2%. Mg - EDTA at 0.1%. 0.2% and 0.3%. The results indicated that. Mg — EDTA at 0.3% gave the heaviest clusters and increased number of berries 1 cluster and beny dimensions. Moreover. Mg — EDTA and Ca - EDTA at 0.3% increased dimensions of cluster. berry weight and size. All calcium treatments. especially In the chelated form. increased significantly the berry firmness. adherence strength of berry. decreased berry shattering percentage before and after storage at room temperature and decreased the decay and loss In fresh weight percentage estimated 4 days after harvesting at room temperature compared to the control and Mg applications. The best results of these parameters were obtained by Ca — EDTA spray at 0.3% followed by Ca — EDTA at 0.2%. T.S.S. (%). acidity (%) and T.S.S I acid ratio were not aflected by Ca or Mg applications either in the mineral or in the chelated form. The obtained results suggested spraying calcium and magnesium in the chelated form at 0.3% on Thompson Seedless rapevines three times In each season. i. e. at the beginning of vegetative growth (2 week of March). immediately after fruit set (1" week of May) and 4 weeks later (1" week of June). to improve the properties of fruit quality and keeping quality during storage at room temperature.