Abstract: In this study, the phylogenetic relationships among twelve lines of Cucumis sativus were studied using Randomly Amplified Polymorphic DNA (RAPD) markers. A modified CTAB DNA extraction protocol was introduced to obtain genomic DNA from young leaves. Of forty random primers tested, only fifteen primers were able to successfully amplify all genomic DNA samples and the results obtained were interpreted based on total and polymorphic scores. A total of 187 bands were produced in which 144 (~77%) were polymorphic. Additionally, a phylogenetic tree was constructed using the UPGMA analysis. Based on the results, the cucumbers examined could be divided into two major subgroups in which the similarity values were between 0.67-0.93.