Technical Abstract: The use of biodegradable and biocompatible polysaccharides as DNA carriers has high potential for gene therapy applications. Pectin is a structural plant polysaccharide heterogeneous with respect to its chemical structure. It contains branches rich in galactose residues which serve as potential ligands for membrane receptors interaction. In order to make the anionic citrus pectin applicable for DNA complexation, pectin was modified to carry primary amine (Pectin-NH2, P-N), or quaternary ammonium groups (Pectin-N+H(CH3)2, P-Q), or a mixture of the both (P-NH2-Q). All modified pectins formed complexes with plasmid DNA as indicated by gel electrophoresis analysis. The size and morphology of pectin-NH2/DNA complexes were examined by transmission electron microscopy (TEM). Transfection experiments were carried out with human embryonic kidney cell lines (HEK293), using plasmid DNA encoding for green fluorescence protein (GFP). Transfection efficiency was analyzed by flow cytometry analysis, using FACS. P-NH2-Q was the most efficient carrier. Addition of chloroquine ("lysosomotropic" agent) to transfection medium substantially enhanced the HEK293 transfection. This indicates that endocytosis is the preferable internalization pathway. Pectin’s galactose residues contribution to transfection was examined by inhibiting pectin binding to membrane receptors (galectins), using galactose and lactose as competitive inhibitors to this interaction. Resulting reduction of transfection efficiency demonstrated the importance of pectin’s galactose residues to HEK293 transfection.