Since the beginning of the XXth

century, single cell protein production has represented a

biotechnological option, which viability has been much

argued, for the handling and profitable disposal of large

amounts of agricultural and industrial waste materials. Due to

the nature of this process, lots of pollution sources can be

transformed into useful materials with industrial, nutritional

and economical value. This paper overviews the historical

evolution of single cell protein, its importance and

applications, advantages and disadvantages of its use in

industrial processes, the main microorganisms known to be a

source of SCP, the most representative substrates used for

their growth, the biochemistry and key operations of the

industrial process, general economical facts and future

prospects. Nutritional aspects such as composition,

nutritional value and limitations of SCP as a source of protein

for human consumption are also reviewed.