Alternaria spp. are known for causing leaf spots and blight, rotting of fruits and seeds. These pathogenic species have spread worldwide, mainly affecting field crops including Cucurbitaceous vegetables. Fourteen cucurbits were observed to be parasitized by four species of Alternaria viz., A. alternata, A. citrullicola, A. cucumerina and A. tenuissima causing leaf spot/blight and fruit rot. A. cucumerina was associated with all the cucurbits except A. citrullicola which caused fruit rot in watermelon (Citrullus lanatus). Three species caused leaf spots/blight and rotting of fruits while A. tenuissima caused only fruit rots. Symptoms of disease, description of causative fungus, morphological differentiation of Alternaria spp. and framing of suitable key for readily identification of four species of Alternaria have been described in this communication.