DNA's remarkable molecular recognition properties, flexibility, and structural features make it one of the most promising scaffolds to design a variety of nanostructures. During recent decades, two major methods have been developed for the construction of DNA nanomaterials in a programmable way; both generate nanostructures in one, two, and three dimensions. The tile-based assembly process is a useful tool to construct large and simple structures; the DNA origami method is suitable for the production of smaller, more sophisticated and well-defined structures. Proteins, nanoparticles and other functional elements have been specifically positioned into designed patterns on these structures. They can also act as templates to study chemical reactions, help in the structural determination of proteins, and be used as platform for genomic and drug delivery applications. In this review we examine recent progresses towards the potential use of DNA nanostructures in molecular and cellular biology.