This work was carried out in order to develop early flowering barley lines. These lines will be useful to producers by enabling multiple crops within a single season and increasing production. Transgenic barley plants containing the natural early flowering time AtCRY2 allele from the Cape Verde Island (Cvi) ecotype of Arabidopsis have been generated using biolistic transformation. Immature embryo derived calli of two commercially important barley cultivars (El-Dwaser and El-Taif), were transformed using a pCAMBIA-2300 plasmid harboring a genomic fragment containing the AtCRY2-Cvi allele. Transformation was performed utilizing 600 immature embryos for each cultivar. Stable transformation was confirmed in T 0 and T 1 plants by using genomic PCR, RT-PCR and western blot analysis with AtCRY2 specific primers and antibodies, respectively. The transformation efficiency was 5.6% and 3.4% for El-Dwaser and El-Taif cultivars, respectively. Seeds from several T 1 lines were germinated on kanamycin plates and the lines that contained a single locus were selected for further evaluation. The transformed barley plants showed the specific AtCRY2-Cvi flowering phenotype, i.e. early flowering and day length insensitivity, compared to the non transgenic plants. The time to flowering in transgenic T 1 plants was assessed and two lines exhibited flowering more than 25 days earlier than the parental cultivars under short day conditions.