Abstract: The invention relates to stereoselective peptide dendrimers for nucleic acid transfection comprising the formula (D3)8-(B3-D2)4-(B2-D1)2-B1—Z (1), wherein Z is a hydrophobic core with Z being —XY1 (1a), —XY2XY2 (1b), —XY3Cys (1c) or —HP (1d), X is selected from Lys or Glu, and each Y is fatty or amine acids, HP is a hydrophobic peptide consisting of 3 to 5 hydrophobic amino, B is Lys and each D independently from any other D is a dipeptide consisting of one hydrophobic amino acid and one cationic amino acid (HC or CH), a dipeptide consisting of two cationic amino acids (CC) or a dipeptide consisting of two hydrophobic amino acids (HH). The invention further comprises a method for transfecting a cell (ex vivo) using the above-mentioned dendrimer.