Bioremediation processes are negatively affected by the low aqueous solubility of some contaminants; therefore their bioavailability may be enhanced by the addition of surfactants. These compounds are organic molecules that can be chemically and biologically produced. Surfactants contain both hydrophilic and hydrophobic groups, therefore reducing surface and interfacial tensions of immiscible fluids and increasing the solubility and sorption of hydrophobic organic and inorganic compounds. This article provides an overview of characteristics of natural and synthetic surfactants and the effects of biosurfactants on solubility, sorption and biodegradation of hydrophobic organic contaminants; as well as the effects of biosurfactants on degrader microorganisms as white-rot fungi. Finally, some examples of application of natural surfactants for bioremediation of contaminated soils are shown. In general, this overview indicates the great potential of biosurfactants on the remediation of contaminated sites.