In today’s modern world, customers require a high level of power quality than ever before because of the increasing availability of semiconductor devices and microprocessors that are more sensitive against power system disturbances. One of the most frequently occurring types of power quality disturbances are voltage sags, which are considered to likely have a severe impact on sensitive load. Thus, power quality monitors (PQM) are required to be installed in many buses in a power system to assess disturbances such as voltage sags. However, the installation of PQMs at all buses considered in the system is uneconomical. Generally, PQM placement comprises four main methods, namely, monitor reach area, covering and packing, graph theory, and multivariable regression. This paper presents a comprehensive review of articles that deal with various methods of PQM placement. The concepts as well as the advantages and disadvantages of these methods are discussed and tabulated for an all-exclusive review. Although this paper does not show a comparison of numerical performance, most of the research publications on the subject of PQM placement methods are sorted and appended for easy reference. This work may be considered as an important guide for researchers who are interested in knowing and developing better PQM placement methods.