Background: α -thalassemia trait is frequently encountered in Saudi Arabia with a large diversity and geographical variability in the underlying genotypes. Aim of Study:To characterize the molecular spectrum of α -thalassemia in the western province of Saudi Arabia in some Saudi patients suspected of α thalassemia carrier or diagnosed with Hb H disease to determine if there is the significance of premarital genetic testing for α thalassemia in a couple suspected with α thalassemia trait.Patients and Methods: This study included 39 patients, 34 patients with suspected α thalassemia trait and 5 patients diagnosed with Hb H disease.Results: Thirteen patients 33.3% are heterozygous for + thalassemia having the genotype --3 . 7 / and 14 patients 35.9% are homozygotes for 0 having the genotype -3 . 7 / -α 3.