ZUCCHINI YELLOW MOSAIC VIRUS (zymv, POTYVIRUS) IS ONE OF THE MOST DAMAGING ‘EMERGING’ VIRUSES OF CUCURBITS .zymv WAS FIRST ISOLATED IN 1973 AND DESCRIBED BY LISA ET AL. IN 1981, IS THE CAUSE OF ONE OF THE MOST ECONOMICALLY IMPORTANT DISEASES OF THE FAMILY CUCURBITACEAE, NATURALLY INFECTING PLANTS IN MORE THAN 50 COUNTRIES. zymv BELONG TO THE POTYVIRUS GENUS AND POTYVIRIDAE FAMILY THE SYMPTOMS OF zymv IN DIFFERENT CUCURBITS INCLUDE STUNTING, YELLOWING, MOTTLING, SEVERE MOSAIC, LEAF AND FRUIT DEFORMATION, BLISTERING AND SHOE STRING. SAMPLES WERE COLLECTED FROM SEX MAIN CUCURBITS CULTIVATION REGIONS OF KHUZESTAN PROVINCE NAMELY SUSH, SHUSHTAR, MOLASANI, HAMIDIEH, DEZFUL, DASHTE AZADEGAN. TOTAL RNA WERE EXTRACTED WITH PHENOL-CHLOROFORM METHOD. FOR RT-PCR, REVERSE PRIMER(R-DAG) WITH THIS SEQUENCE “GCGTGGCAATGACAT” WHICH IS LOCATED IN 8735-8749 OF GENOME OF zymv. THE FRAGMENTS WITH 458 BP LENGTH WERE AMPLIFIED IN EACH ISOLATES. THE FRAGMENTS OF ISOLATES WERE SEQUENCED FROM BOTH DIRECTIONS. SEQUENCES OF SEX ISOLATES WERE COMPARED USING CLUSTALW ALGORITM USING MEGA4 PROGRAM. NUCLEOTIDE SEQUENCE DATA WERE ANALYZED USING BLAST PROGRAM AT NCBI WEBSITE. PHYLOGENETIC TREE ANALYSIS WAS CARRIED OUT USING THE NEIGHBOR-JOINING METHOD WITH BOOTSTAP1000 OF MEGA4 PROGRAM. AFTER COMPARISON OF 400 NUCLEOTIDE SEX ISOLATE SEQUENCE, THE SAME SEQUENCE IN THIS REGION (NIB-CP) WERE OBSERVED. SHUSH ISOLATE WAS SELECTED AND WAS RECORDED IN NCBI WITH THIS ACCESSION NUMBER (FJ270312). SHUSH ISOLATE SEQUENCE WAS COMPARED OTHER SEQUENCE USING BLAST IN NCBI WEBSITE. THIS ISOLATE WAS CLOSED CALIFORNIA ISOLATE WITH 97% MAX IDENTITY. PHYLOGENTIC TREE WAS DESIGNED USING 63 ISOLATE FROM SEVERAL COUNTRIES. SHUSH ISOLATE SEQUENCING BLAST IN NCBI WAS SHOWED SHUSH ISOLATE WAS CLOSER ASADABAD ISOLATE (HAMEDAN) WITH 98% SIMILARITY THAN IRANIAN ISOLATES. AND ALSO BLAST SEQUENCE OF THIS ISOLATE WAS ILLUSTRATED SHUSH ISOLATE MORE CLOSELY CALIFORNIA STRAIN (97%).