2,4,6-Trinitrotoluene (TNT), historically the most widely used explosive, is still being frequently detected at the sites of military and/or civilian applications in combination with other nitro explosives and multiple explosive derivatives. Because of their established toxicity and mutagenicity for many organisms, bioremediation of sites contaminated by nitro explosives is a priority. Over the last 30 years, promising microbial degradation pathways of nitro explosives have been discovered. However, their long-term persistence in the environment, primarily that of TNT, underscores their low intrinsic biodegradability, the rate-limiting nature of environmentally occurring processes, and the multiscale complexity of contaminated field sites, which limits the implementation of in situ bioremediation. Therefore, this article gives an overview of the recent advances made in the genetics and biochemistry of biodegradation of nitro explosives, with special emphasis on promising enzymatic families, such as the Old Yellow Enzyme (OYE) family, the class VI cytochrome P450 system, and the family of nitronate monooxygenases or nitroalkane oxidases. Since co-contamination by different classes of nitro explosives with specific biodegradation and transport patterns is commonly observed in investigated sites, a holistic approach is required to more effectively assess, optimize, predict, and proactively support the performance of a bioremediation process that must integrate multiple biodegradative machineries and biomonitoring circuits. © 2011 Elsevier B.V. All rights reserved.