The present state-of-the-art of silicon high concentration solar cells is reviewed. Two cell structures, the silicon point contact cell and the microgrooved cell structure, have demonstrated efficiencies of 28% at 150× and 24.7% at 100×, respectively. The problems associated with operation at high concentration are discussed. It is noted that Auger recombination is the limiting factor in the operation of high efficiency solar cells, affecting not only the open circuit voltage, but having a great impact on the short circuit current as well. With additional design improvements, efficiencies over 30% at concentration appear to be within reach.