We used an RNAi based approach to induce post-transcriptional gene silencing of the MdTFL1 gene in apple in order to reduce the juvenile phase. The MdTFL1 protein is homologous to TFL1 of A. thaliana which suppresses the floral meristem identity genes LFY and AP1 and maintains the inflorescence meristem. A binary vector was constructed which contains a constitutively expressed nptII gene and a chimeric gene construct encoding for a hairpin RNA homologous to the coding sequence of MdTFL1. The vector was used to transform the apple (Malus domestica Borkh.) cvs. ‘Holsteiner Cox’ and ‘Gala’ via Agrobacterium tumefaciens-mediated transformation. Regenerated shoots were proven for transgenity by Southern blot and RT-PCR. Quantitative real time PCR analysis showed that the expression of MdTFL1 was markedly reduced in transgenic lines compared to non-transformed control plants. The regenerated transgenic plants started to flower six month after the transformation under in vitro conditions. The plants were recently transferred to the greenhouse where they continued to flower.