The discharge of drilling mud as well as the release of crude petroleum and petroleum products into human environments have resulted in many problems that are of much concern globally. Indiscriminate disposal of spent oil-based drilling mud during after drilling activities often results to pollution of the environment posing threat to the biota of aquatic and terrestrial ecosystems. This book demonstrated the applicability of two Pleurotus species in bioremediation of spent drilling mud impacted matrix. The work presented here would benefit student and researcher interested in environmental remediation.