Since the discovery of the RNA interference (RNAi) in 2006, several attempts have been made to use it for designing and developing drug treatments for a variety of diseases, including cancer. In this mini-review, we focus on the potential of small interfering RNAs (siRNA) in anticancer treatment. We first describe the significant barriers that exist on path to clinical application of siRNA drugs. We then review the current delivery approaches of siRNAs using lipids, polymers, and, in particular, polymeric carriers that overcome the aforementioned obstacles. Additionally, we collate a list of siRNA databases, along with a qualitative and/or quantitative summary of the data in each database. This mini review aims to facilitate our understanding about the siRNA, their delivery systems and the possible barriers in their in vivo usage for biomedical applications.