The invention relates, inter alia, to a beam guidance system for guiding a beam of charged particles with a magnetic beam deflection unit, wherein the magnetic beam deflection unit has an entry side for entry of the beam of charged particles into the magnetic beam deflection unit in a direction of entry, wherein the magnetic beam deflection unit has an exit side for exit of the beam of charged particles from the magnetic beam deflection unit in a direction of exit. A further aspect of the invention relates to an advantageous particle beam therapy system. The problem of providing improving beam properties and at the same time reducing the amount of space required is solved in that the entry side of the magnetic beam deflection unit is, at least in sections, aligned substantially parallel to the exit side of the magnetic beam deflection unit.