Cucumber mosaic virus (CMV) was isolated from naturally infected cucumber plants Cucumis sativus L. grown in various garden and greenhouses of Ismailia Governorate, Egypt exhibiting systemic mosaic, blistering, fruit malformation and stunted plant growth and identified by biological, serological and molecular analysis. The isolated virus gave positive reaction with CMV antiserum but not with antibodies of WW and SqMV using DAS-ELISA. CMV was able to infect different host plant species including squash, pumpkin, pepper, bean, Chenopodium amaranticolor and cowpea showing foliar symptoms of mosaic, deformations and necrotic and chlorotic ring spots, that resemble those induced by CMV. SDS-PAGE test showed various distinguishable sole novel protein bands in four cucumber cultivars infected with CMV but not in healthy one. RT-PCR, with the primer CMV 1 and CMV2 for CMV-CP. gene, yielded 422 base pair DNA fragments. The following sequences were used in the comparison: Brazil (AF418577), China (FJ403473), New Zealand (AY861395) and India (AJ810260). The partial nucleotide sequence alignment, showed (95%) homology between CMV New Zealand isolate and CMV-Egyptian isolate. The sequence alignment also indicated that the CMV isolate is far from similarity with India CMV, showing (92%) according to the phylogenetic homology tree , which were 92 to 99% identical to those of CMV- Egypt isolate.