Inside in this book, we have described the uses of nitroaromatics and their impact on the eco-geological system. Also, we have described their toxic effects, for example, several nitro group containing aromatics are considered as poison, when they accumulate in the body by various routes like inhalation, subcutaneous, consumption, intraperitoneal, intramuscular or even directly from skin, rapidly they start to implicate there toxic effect in the living system. The basic information of mono-nitroaromatics degradation by different organisms was also included. Microbial transformation of nitroaromatics can be categorized as aerobic and anaerobic routes.