Distributed generation is one of the new trends in power systems used to support the increased energy-demand. Distributed generation is an electrical source connected to the power system, in a point very close to or at consumer’s site which is small enough compared to the centralized power plants. Continuous demand for stable power supply by the end users of electricity necessitates the integration of DG directly to distribution system of a power network. If DGs are optimally sized and sited in the distribution network, power system reliability, stability and efficiency are guaranteed since they cut off losses associated with transmission system. Besides, more than 95% of total power generated can be effectively harnessed by the end users. This paper presents a comprehensive survey of DG integration on utilities distribution system of apower network with a view to measuring the extent of DG Integration on Nigerian Grid and to find out the most commonly used techniques for the optimal placement and sizing of DG problems. The results of this research paper shows that the work done on Nigerian radial distribution system is about 13.20% and this is largely due to scanty availability of Nigerian radial distribution system data. The most commonly used techniques for the optimal placement of DG are genetic algorithm and its variant which is about 25.71% in relation to other evolutionary algorithms based on the volume of paper reviewed.