Thalassemia is one of the most common hereditary disorders in the Mediterranean region. We report here the results of a premarital screening carried out in Adıyaman in the southeastern region of Turkey, a region with a hitherto unknown incidence of β-thalassemia (β-thal). In order to detect β-thal carrier frequency and genotypes of carriers from the city of Adıyaman, Turkey, both high performance liquid chromatography (HPLC) and the red blood cell counts of 1616 people who applied for premarital tests were analyzed. Blood cell counts were measured by a cell counter and the hemoglobin (Hb) fractionation was carried out by HPLC. The frequency of β-thal carriers in the city of Adıyaman was 1.91% and the frequency of abnormal Hbs was 0.07%. We report 28 chromosomes of β-thal traits with 10 different mutations, including the first report of codon 17 (AAG>TAG) in Turkey and one individual who was heterozygous for Hb D-Los Angeles [β121(GH4)Glu→Gln, GAA>CAA]. This study was the first to be performed on the frequency and molecular pathology of β-thal mutations in Adıyaman in the southeastern region of Turkey. We report that the prevalence of the thalassemia trait is similar in all regions of our country, but the prevalence of mutation heterogeneity varies from region to region.