Sweet basil (Ocimum basilicum L., Lamiaceae), an important medicinal plant and culinary herb due to its delicate aroma and fragrance, shows great variation in both morphology and essential oil components. Genetic variation among basil accessions in Turkey has not been extensively examined with molecular markers. Genetic diversity was determined using random amplified polymorphic DNA (RAPD) markers of 14 genotypes of basil. A total of 375 bands were obtained from the RAPD analysis, and 273 of them (70.3 %) were polymorphic. The RAPD analysis allowed the grouping of samples into two main clusters. Genetic similarity values among the basil genotypes ranged between 0.46 and 0.87. Considerable genetic diversity was determined among basil genotypes. Essential oils were obtained by hydro-distillation and were characterized by gas chromatography. A total of 17 chemical components were identified. The evaluated genotypes of O. basilicum can be classified into seven chemotypes: (1) Linalool (7, 12, 16, 22, 25A and 33), (2) Methyl chavicol (6, 10A), (3) Citral/methyl chavicol (10L, 17), (4) Methyl eugenol (11), (5) Methyl cinnamate/linalool (23), (6) Linalool/methyl eugenol (25K), and (7) Methyl chavicol/linalool (Let). The chemical variability obtained from the essential oil composition of the genotypes in the study was remarkable. The chemical characterization of genotypes 10L and 17 was rich in citral (42.17 and 44.80 %) and methyl chavicol (30.56 and 32.03 %). Citral/methyl chavicol can be assessed as a new chemotype of basil cultivated in Turkey. The basil genotypes were grouped into two major clusters for both the RAPD analysis and chemical characterization with very few exceptions (genotype n. 6). A correlation analysis of the genetic distance matrix and the Euclidian distance matrix showed relatively low values (r = -0.40). The results demonstrated a certain degree of correspondence between chemical and molecular data.