Cucumber mosaic virus (CMV) is one of the most prevalent viruses of cucurbit plants in Iran. In this research, the reaction of 40 commercial varieties of cucurbit including cucumber, squash, watermelon and melon was investigated against a CMV isolate under greenhouse condition. This study was performed based on completely randomized design with 10 replications.The seedlings were inoculated using CMV-infected tobacco (Nicotiana glutinosa) sap at 3-5 leaf stage and their reaction was evaluated based on symptom severity index and ELIZA OD405 values four weeks after inoculation. Each inoculated plants was graded using a 0-5 scale (0, plants free for symptoms; 5 plants showing blistering and malformation). The result of this study indicated that genotypes have appropriate genetic diversity for disease resistance and classified in five groups including highly susceptible, intermediate susceptible. moderately resistant, resistant and highly resistant. Contingency table in chi-square test showed significant interaction between genotypes and disease symptoms. In accordance with evaluated parameters, reaction of varieties to the virus was significantly different. At probability level of 1%, all watermelon genotypes (101, 104, 108, 120, 123, 201, Farao, Super Dragon and Charleston Gray) and some melon genotypes including (Tempo, Yellow Canaria, Minnoo and flat, June des Niagara), cucumber genotypes (Beit Alpha, Super N3) and squash (Ghaliaei genotype) were resistant (R) andhighly resistant (HR), respectively . In addition, 16 genotype moderately resistant (MR), two genotype (Revena and yellow) were resistant (R), two genotype intermediate susceptible (S) (Gavrish and Shabestar). Finally one genotype of squash (Niagara and Squah Shiraz) was highly susceptible (HS).