Study of the machinability characteristics of porous sintered materials has received far less attention during the last decades, presumably due to powder metallurgy's greatest advantage over other manufacturing methods in eliminating completely or minimising greatly machining and also perhaps due to lack of any standard test method developed for machinability studies. However, many parts because of intricate design, require machining afterwards. Thus, there is a renewed interest in machinability characteristics of sintered porous materials. Various investigations on machinability studies of sintered ferrous materials have been reviewed in this study. Finally, the effect of some usual additives and microstructural modification on the machinability of sintered and heat-treated steels has been examined. The method used was time taken by a drill of standard dimension before it broke down. Increasing C-content was found to have marginal while usual alloying elements like Cu, Ni, etc, had significant effect on machinability characteristics of sintered steels. It has been concluded that combination of parameters affecting machinability of P/M materials may prove to be beneficial and effective method to control machining characteristics of sintered steels.