The present invention relates to cationic lipids capable of forming complexes with nucleic acids and the use thereof for the transfection of eukaryotic cells. The cationic lipids according to the invention have general formulas (I) and (Ia): (see formulas (I) and (Ia), wherein E is a heteroaryl; Rl and R2 are selected from H, -R7-NH2, -CH-NH-NH2, alkyl; R7 is selected from alkyl, alkenyl, aryl, (C1-C20) alkyl-aryl- (C0-C20) alkyl; R3 and R4 are selected from: H, -R8-SH, -R8-NH-NH2/ -R8-CO-R9 or - R8-NH2; R8 is selected from: alkyl, alkenyl, aryl, (C1- C20) alkyl-aryl- (C0 -C20 ) alkyl; R9 is selected from: H, alkyl; R5 and R6 are selected from: H, alkyl, alkenyl, aryl, (C1-C20) alkyl-aryl.