Experiments were conducted during four consecutive seasons of 2017, 2018, 2019 and 2020 on three grape cultivars including “Bez-El-Anza”, “Thompson Seedless” and “Red Roomy” planted at the Experimental Orchard of fruit section, Faculty of Agriculture, Assiut University in a complete randomized blocked design. This investigation was carried out to study the effect of spraying Seaweed extract, Amino acids and Vitamins on C/N ratio, yield and berry quality of some grape cultivars. The obtained results showed that Tyrosin at 500 ppm recorded the highest yield (9.47 kg/vine) during the 1st season. All treatments had a significant impact in the respect of TSS %, acidity% and TSS/acid ratio. Concerning C/N ratio, Vit.B12 at 150 ppm recorded the highest ratio (44.85) during the 1st season. Hence, the present study concluded applications of Seaweed extract, amino acid and Vitamins improved vine C/N ratio, yield and berry attributes of “Bez-El-Anza”, „Thompson Seedless‟ and “Red Roomy” grape cultivars.