Microscopic blue-green Spirulina algae, such as have been consumed since ancient times, are algae having a very high protein content (70 p. 100 of dry matter). At present the Spirulina platensis species in the Kanem region in Chad is gathered by primitive methods, sold in the marketplace and consumed by the local population. The Spirulina maxima species exists in a seminatural state in Mexico City, and an industrial pilot plant harvests and produces one ton per day. Both species, Sp. platensis and maxima, can be cultivated in the same way in a controlled synthetic medium in large-area basins. Whether these Spirulina come from a natural medium or synthetic culture basin, harvesting includes the successive stages of concentration, filtration and washing followed by drying done in a conventional manner. The characteristic constituents of Spirulina platensis and Spirulina maxima, in addition to the high protein content, are both nucleic acids that account for about 4 p. 100 of the dry matter and the fatty-acid composition which is saturated C16 and ethylenic C18 substances. Linoleic acid and especially gamma-linolenic acid arecharacteristic of these two species. The unsaponifiable content is made up in particular of sterols such as cholesterol and beta-sitosterol as well as by triterpenic alcohols such as alpha-amyrin.