We describe 27 cases of mild-to-severe α-thalassemia (α-thal) syndrome caused by interaction of Hb Adana [α59(E8)Gly→Asp, GGC>GAC (α2)] with deletional and nondeletional α(+)-thal mutations in Indonesian patients. Hematological profiles and clinical manifestations of all patients were assessed by routine procedures. The genotypes were generated by a multiplex-polymerase chain reaction (m-PCR), PCR-RFLP (restriction fragment length polymorphism)-based method, and DNA sequencing. The α-thal patients who had Hb Adana in combination with the 3.7 kb deletion mostly have mild-to-moderate anemia. In contrast, patients who were compound heterozygotes for Hb Adana and nondeletional mutations, generally showed a more severe anemia and it mostly presented in childhood. Thus, accurate diagnosis of α-thal disorders is not only important for future management of these patients but also for providing proper genetic counseling to the family.