Downy mildew (Plasmopara viticola) is one of the most widespread fungal diseases, with a major impact on plant health and berry quality. The present study aims to describe the symptomatic response of Muscat Ottonel and Chasselas varieties grown in vineyards in eastern Romania and to highlight the manifestations of the infection at the visual and microscopic level. Observations were made during the active vegetative stages of the leaves and berries, with the symptoms of the disease being qualitatively documented through visual observations and photographs, and microscopic images were used to confirm the presence of the mycelium and characteristic spores of Plasmopara viticola. Initial symptoms included the appearance of yellow spots on the upper leaves, followed by the development of white mycelium on the lower side of the leaves. Microscopic images revealed dense mycelium and spores of the pathogen, confirming the nature of the infection. As the berries and young shoots were affected, discolorations and necrosis were observed. Differences in symptom intensity were noted between Muscat Ottonel and Chasselas cultivars, indicating variability in susceptibility to infection. Qualitative observations and microscopic images provide relevant information on the progression and manifestations of downy mildew, contributing to the understanding of the interaction between vines and the pathogen. These data can be used for the selection of resistant cultivars and the development of sustainable vineyard management strategies.