The cis-acting elements were scanned within 11.5 kb of the 3′juxtaposed region of the Yunnanese (Aγδβ)⁰-thalassemia deletion using the luciferase report gene system. A 1.7 kb fragment immediately downstream of the 3′ breakpoint of the deletion was found to increase expression of the luciferase gene driven by Gγ-globin gene promoter by 3.8 to 4.0 fold in K562 cells and MELGM979 cells and 1.5 fold in HeLa cells. A 1.4 kb fragment that is located 10 kb downstream of the 3′ breakpoint was found to increase the luciferase expression by 2.4 to 2.9 fold in K562 cells and MELGM979 cells but no enhancement in HeLa cells. The results suggested that the two fragments contain enhancer-like elements and they function in a certain erythroid-specific manner. Furthermore, a 430 bp region that contains several putative motifs for known transacting factors binding within the 1.7 kb fragment was showed to include the most of the enhancer activity of the fragment. These results provided experimental proof for the hypothesis that the importation of enhancer-like sequences into the vicinity of Gγ globin gene may be responsible for the reactivation of the Gγ-globin gene in the Yunnanese (Aγδβ)⁰-thalassemia mutant.