Combining physics, engineering, chemistry and biology, we can now design, synthesize and fabricate biological nanomaterials at the molecular scale using self-assembling peptide systems. These peptides have been used for fabrication of nanomaterials, including nanofibers, nanotubes and vesicles, nanometer-thick surface coating and nanowires. Some of these peptides are used for stabilizing membrane proteins and drug delivery, and others provide a more permissive environment for 3D cell culture, tissue engineering and repair of tissues in regenerative medicine. Self-assembling peptides are also useful for fabricating a wide spectrum of exquisitely fine architectures, nanomaterials and nanodevices for nanomedicine and nanobiotechnology. These peptide systems lie at the interface between molecular biology, chemistry, materials science and engineering. The studies of designed self-assembling peptides and their applications will help us to understand nature?s enormous power and how to apply it to benefit other disciplines and society.