Double stranded short interfering RNAs (siRNAs) mediate gene silencing in a sequence specific manner. By virtue of their specific gene silencing activity and owing to the recent discoveries on their plasmid and virus driven expression, siRNAs are being widely adopted in research and therapeutics. Efforts were made to optimize the siRNA expression system for the application in therapy. One major obstacle in developing RNA interference (RNAi) therapy is the delivery of siRNAs to the target cells. Combination of novel molecular targeting technologies, such as recombinant protein technology and ribosome display technology, will enable to deliver gene silencing agents to target cells specifically and efficiently.