During the winter season of 2011, a sever Sclerotinia blight disease symptoms were observed on cucumber plants grown in the Protected Cultivation Station, Ministry of Agriculture located at Tookh province, Qalubiya governorate. Disease symptoms (Fig. 1) become visible on plant branches, leaves, flowers and fruits. In a cool moist environment, which normally provided under greenhouses conditions, watery soft lesions occur at sites of infection and the tissues are rapidly covered with white fluffy mycelium. The leaves become chlorotic and necrotic, and stems become girdled and die. On the dead plant tissues as well as within tissues of stems and fruits, fungal sclerotia are formed. The causal fungus was isolated and identified as Sclerotinia sclerotiorum (Lib.) de Bary. According to the available literatures, this is thought to be the first record of Sclerotinia blight disease of cucumber in Egypt.