Discharge of heavy metals from metal processing industries is known to have adverse effects on the environment. Conventional treatment technologies for removal of heavy metals from aqueous solution are not economical and generate huge quantity of toxic chemical sludge. Biosorption of heavy metals by metabolically inactive non-living biomass of microbial or plant origin is an innovative and alternative technology for removal of these pollutants from aqueous solution. Biosorption is regarded as a potential costeffective biotechnology for the treatment of high volume low-concentration complex wastewaters containing heavy metals. Some factors such as solution pH may affect biosorption process. The equilibrium of biosorption process can be described by isotherm models such as Langmuir and Freundlich. A vast array of biological materials, especially bacteria, algae, yeasts and fungi have received increasing attention for heavy metal removal and recovery due to their good performance, low cost and large available quantities, have been reviewed in this paper. Tree bark is among the widely available and low-cost sorbents for metal adsorption in aqueous environments. Peat is also a type of commonly used biosorbent.