Bergamot (Citrus bergamia Risso) fruit extracts as inducers of gamma-globin gene expression. Epicarps of Citrus bergamia fruits from organic farming have been extracted with the object to obtain derived products differently rich in coumarins and psoralens. The extracts were chemically characterized by 1H-NMR, GC-FID, GC-MS and HPLC for detecting and quantifying the main constituents. Both bergamot extracts and chemical standards corresponding to the main constituents detected were then assayed for their capacity to increase erythroid differentiation of K562 cells and expression of gamma-globin genes in human erythroid precursor cells. Three experimental cell systems were employed: (a) the human leukemic K562 cell line, (b) K562 cell clones stably transfected with a pCCL construct carrying green-EGFP under the gamma-globin gene promoter and (c) the two-phase liquid culture of human erythroid progenitors isolated from healthy donors and beta-thal patients. The results demonstrate that citropten and bergapten are powerful inducer of erythroid differentiation and HbF production, when compared with other known inducers.