Bioremediation is a technology in which environmental contaminants are exposed to microorganisms or plants that convert these pollutants to nontoxic or less toxic products. Nowadays, this technology shows promising result for the decontamination or degradation of orthodox pollutants that are very tedious to manage by natural means. Modern technologies are available for the removal of hydrocarbons from water and soil, but all these techniques are complex and have a high cost of operation. In contrast to these physical, chemical and mechanical procedures, bioremediation processes have certain advantages. A number of bacteria and fungi are known for biodegradation of petroleum hydrocarbons and their derivatives. The present chapter focuses on the importance of microbial-based remediation of hydrocarbons.