The production of fruits and seeds of many crops is increased when external pollination occurs. Although self pollination is a widespread biological process in cultivated grapevines, there are still some uncertainties about the consequences of cross fertilization regarding productivity and quality of grapevines. Fertilization biology of grapevines becomes an essential issue when protected cultivation in particular is considered. The present investigations were therefore performed to clarify the possible effects of different pollination treatments on the agronomic features of ‘Perle de Csaba’ and ‘Trakya İlkeren’ table grape cultivars. Before the anthesis, clusters of self-pollination treatment were enclosed within cheesecloth frames to avoid extraneous pollination. For the free pollination group, flowers of twelve similar clusters were allowed to bloom and pollinate spontaneously, while hand pollination was performed by transporting the mixture of external pollens gathered from different cultivars at bloom stage. In ‘Perle de Csaba’ cultivar, hand pollination and free pollination treatments significantly increased the overall agronomic parameters on berry set rate, berry development, cluster size, seed weight and seed size in comparison to self pollination. Treatments had similar effects in ‘Trakya İlkeren’, except for a few parameters such as cluster length, berry diameter and seed thickness. Overall results indicated that cross pollination would considerably increase the quantity and quality of table grapes when cultivated under protected conditions such as glass or greenhouses.