Precision studies of the primary cosmic positron spectrum could give us an evidence of dark matter in the universe. Previous experiments reported tantalizing features in both the electron and positron spectra but were not optimized for those measurements. The proposed Positron-Electron Balloon-born Spectrometer (PEBS) therefore seeks to establish a new suborbital programme with a goal of providing essentially background-free measurements of primary electrons and positrons in cosmic rays up to TeV energies. The PEBS detector will consist of a magnet, a transition radiation detector, a time-of-flight system, a novel high-resolution scintillating-fibre tracker and an electromagnetic calorimeter. The concepts, some test beam results and scientific programme will be presented in this talk.