Cucumber (Cucumis sativus L.) is one of the most important summer vegetable crop grown in tropical as well as subtropical region. Cucumber suffer from a large number of viral diseases throught the world. Among these viral diseases, Cucumber mosaic disease caused by Cucumber mosaic virus (CMV) is the most economically important. The disease is widely prevalent in all cucumber growing states including Maharashtra and causes severe losses in cucumber cultivation. In the study, pathogenicity of Cucumber mosaic virus (CMV) was proved by sap inoculation method. All the sap inoculated healthy young cucumber plants showed the symptoms of leaf puckering, vein banding, mosaic, leaf distortion and stunted plant growth. CMV was found in to infect the host species belonging to the families viz, Cucurbitaceae, Leguminosae, Compositae, Amaranthaceae, Solanaceae and Chenopodiceae. physical properties of prevalent Cucumber mosaic virus strain and transmission by the insect vector