Previously, we have reported the synthesis of a homochiral l-cyclic peptide [WR]5 and its use for delivery of anti-HIV drugs and biomolecules. A physical mixture of HAuCl4 and the peptide generated peptide-capped gold nanoparticles. Here, [WR]5 and [WR]5-AuNPs were tested for their efficiency to deliver a small interfering RNA molecule (siRNA) in human cervix adenocarcinoma (HeLa) cells. Flow cytometry investigation revealed that the intracellular uptake of a fluorescence-labeled non-targeting siRNA (200 nM) was enhanced in the presence of [WR]5 and [WR]5-AuNPs by 2- and 3.8-fold when compared with that of siRNA alone after 24 h incubation. Comparative toxicity results showed that [WR]5 and [WR]5-AuNPs were less toxic in cells compared to other available carrier systems, such as Lipofectamine.