The use of modern state-of-the-art device fabrication techniques and the development of new methods of nanosclae material synthesis/manipulation enable us to investigate at the mesoscopic scales. In these length scales the nanoscaled materials have exhibited a variety of unique physical phenomena due to the enhanced quantum confinement of electrons in reduced dimensions. In this presentation, we will discuss our recent investigation of mesoscopic transport phenomena in carbon nanotubes, nanowires, and graphene, where quantum mechanically enhanced low dimensional effects are predominant. The subjects include, (1) growth/manipulation of ultralong nanotubes and electrical characterization of them, (2) electric field effect in mesoscopic thermoelectric transport in nanotubes, (3) electrical transport between nanotube-single molecular junction, (4) 1D to 3D cross-over in electric transport in multichannel nanowires, and (5) unusual quantum Hall effect and observation of Berry’s phase in mesoscopic graphene.