The present study was carried out during 2003, 2004 and 2005 seasons on 15 years old Thompson seedless grapevines grown on a clay soil in a private vineyard at EL-Tawela village near Mansoura city, Dakahlia governorate. The aim of the present study was to investigate the effect of addition different sources of organic fertilizers as a partial substitute for nitrogen mineral fertilizers and their effect on bud behaviour, growth, mineral content of the leaves, yield and quality of Thompson Seedless grapevines. Farmyard manure (FYM), rice straw compost (RSC), Damitta town refuses (DTR) and Mansoura town refuses (MTR) were used with mineral nitrogen source (Ammonium sulphate) during this investigation. All vines were received the same nitrogen requirements (80 units of nitrogen per fed), but with replacement of 25, 50 and 75 % of the nitrogen requirements by organic manures (FYM, RSC, DTR and MTR) according to their nitrogen content. The control vines received the nitrogen requirements as mineral alone. The results showed that all combinations from organic nitrogen (sources + doses) with mineral nitrogen doses increased bud burst %, bud fertility %, fruiting coefficient, number of clusters per vine, cluster weight and yield/vine. In addition, SSC % was increased and total acidity was reduced in the berries juice. The data also indicated an improvement of rate of wood maturity, weight of pruning wood per vine and total carbohydrates in the canes as compared with using mineral nitrogen alone. The superiority of this investigation was for DTR at 40 and 60 units + 40 and 20 units of mineral nitrogen per fed which gave the best results.