The evaluation of grapevine genetic resources is very important especially from the viewpoint of the use of some varieties within the process of grape breeding. At present, the breeding of grapevine is more and more focused upon selection of varieties showing an increased resistance to fungal diseases and, especially to downy mildew. At the Faculty of Horticulture, we have studied the resistance of 32 grapevine varieties to downy mildew resistance on leaves. This evaluation took place under field conditions in a vineyard that was not treated with pesticides within the period of 1996–2000. The resistance to downy mildew was evaluated using a scale published in the “International List for Grapevine Varieties and Species Evaluation”. The highest degree of resistance was observed in the following varieties: ‚Augustovskii', ‚Yalovenskii Ustoichyvii‘, ‚Pőlőskei Muskotály‘, Pleven ustoichyvii, ‚Aivaz‘, ‚Dachnyi‘, ‚Kutuzovskii‘, ‚Nero‘, and ‚Smuglyanka Moldavskaya‘. These varieties can be used as starting material for a further breeding. It can be therefore concluded that studies on genetic resources are very important.