Lomustine is an anticancer drug used to treat brain tumors and Hodgkin’s disease. However, during the manufacturing process of Lomustine, impurities may be formed due to the reaction of the raw materials used. These impurities can affect the quality, safety, and efficacy of the drug. Therefore, it is important to identify and control these impurities by using analytical techniques such as HPLC, GC, and NMR.