High quality olive oil can be produced from a standard cultivar with high olive oil quality. In this study, olive genotypes grown in the Southern Marmara Region has been determined using simple sequence repeats (SSR) markers. A total of 70 samples from 10 major olive growing locations in the Southern Marmara Region were collected. SSR analysis demonstrated that olive production in this region has been made using primarily a single genotype called "Gemlik". There were some genotypes (8%) were misidentified as "Gemlik" by the farmers since their SSR marker profiles were different from remaining "Gemlik" cultivars. Due to the repropagation of "Gemlik" using green cuttings, it has become the major olive cultivar grown in this region. On the other hand, traditional repropagation of olive using grafted seedlings increases time, expenses and technical expertise required for reproduction. Therefore, repropagation of "Gemlik" using green cuttings promoted the distribution this genotype in the Southern Marmara Region. Although "Gemlik" cultivar is popular and primarily consumed as table olive in Turkey, a standard olive oil production can be made using "Gemlik" cultivar grown in this region. Techniques to increase the quality of olive oil produced from "Gemlik" cultivar should be developed in the future.