Parsek2D: An Implicit Parallel Particle-in-Cell Code. A Particle-in-Cell (PIC) code, called Parsek2D, for the simulation of astrophysical and space plasmas is presented. Parsek2D enables simulations with large grid spacing and long time step, by means of implicit time differen- tiation and parallel computing. An implicit formulation of the PIC algorithm removes the severe numerical stability constraints of explicitly time-differenced PIC. Parallel supercomputers are needed to meet the computational and mem- ory storage requirements of large scale problems The implicit PIC algorithm, and its implementation on parallel computers are described. Simulations of magnetic reconnection using physical mass ratio are shown.