[en] New C-periodic boundary conditions, which are topologically different from periodic ones, are introduced to lattice gauge theory. When shifted by L lattice spacings C-periodic fields are replaced by their charge conjugates. In abelian lattice gauge theory C-periodic boundary conditions allow the existence of single charged particles (like monopoles) whereas periodic systems are always neutral. In nonabelian lattice gauge theory C-periodic boundary conditions affect the 't Hooft Z_N flux sectors. For example, in the SU(3) case the flux sectors are entirely eliminated. This has interesting effects on the finite volume glueball mass spectrum and on the finite temperature deconfinement phase transition. (orig.)