The present invention discloses cell penetrating peptides (CPP or membrane translocating peptide) and their conjugates with cargo molecules. The peptides are useful as drug delivery systems, particularly as delivery vehicles for nucleotide-based therapeutics, such as polynucleotides, oligonucleotides and peptide nucleic acids. A CPPs of the invention provides a balance between good cell entry efficiency and low toxicity and comprises three contiguous domains: the central one being hydrophobic and the flanking ones consisting of arginine and aminohexanoic acid or beta-alanine residues. The hydrophobic domain contains a sequence selected from YQFLI, YRFLI, IQFLI and IRFLI.