Bioinformatics is science that applies information technology to manage and analyze biological data, such as sequences of nucleotide, protein or other database. Bioinformatics data could be used to find out the similarity or genetic relationships and protein structure of an organism. In this research, bioinformatics was applied to analyze nucleotide sequences of coat protein (CP) gene among 13 isolate of Cucumber green mosaic viruses (CGMMV). CGMMV is virus belongs to the genus Tobamovirus that infects the plants belong to family Cucurbitaceae. Each isolate of CGMMV has a conserved CP gene with different nucleotide sequence. The purposes of this research was to find the genetic relationships among 13 isolates of CGMMV based on CP gene using bioinformatics. Data were acquired by browsing to GeneBank on National Center for Biotechnology Information (NCBI)site. Nucleotide sequences of CP gene from 13 isolates of CGMMV and one isolate of Kyuri green mottle mosaic virus (KGMMV) as aoutgroup were analyzed by BLAST software on DNA Data Bank of Japan (DDBJ) site, and align by ClustalW software on European Bioniformatics Institute (EBI) site. Results of data analysis showed that two pairs of CGMMV isolates, that is CGMMV-Zucchini with CGMMV-China and CGMMV-LPH with CGMMV-NS have the highest similarity index (100%). However, the lowest similarity index (90,9%) was found between CGMMV-Rajasthan and CGMMV-GRS. Accoring to the similarity index, genetic relationship among 13 isolates of CGMMV coul be devided into three groups, that is East Asia, South Asia and Europe groups
