The weed flora of vineyards in northwestern Turkey was determined in a survey carried out in 93 vineyards. Total of 68 species 53 dicotyledonous and 11 monocotyledonous belonging to 32 families were identified in grape growing areas. The majority of weed species were annual species with different vegetation periods. The dominant weed species in the region were Capsella bursa pastoris, Convolvulus arvensis, Senecio vulgaris, Stellaria media, Sorghum halepense, Euphorbia helioscopia. Meanwhile frequent families were Poaceae, Asteraceae, Brassicaceae, Fabaceae, Geraniaceae, Lamiaceae, Polygonaceae and Euphorbiaceae.