A Zernike phase contrast (ZPC) electron microscope was used to image the known structures of purple membrane 2-D crystal and ε15 phage particles. The reconstructions of these two specimens show the feasibility of resolving long alpha helices of the protein subunits at subnanometer resolutions. The ZPC single particle images of ε15 phage particles allows us to obtain a higher resolution structure with lesser number of particles than that determined with conventional images. In a cryo-electron tomography study, post-tomographic averaging of subtomograms from a single tilt series of ice embedded ε15 phages yields a density map at a resolution better than that with conventional images. These results demonstrate the potential advantages of this novel imaging modality for molecular and cellular structure research.