This study was designed to explore the nutritional value of proteins derived from algal biomasses of genus Spirulina maxima, with a view to the possible use of such proteins in human alimentation. Recently the use of such biomasses has commanded attention both as an alternative source of alimentary protein and as a coadjuvant in diet treatment requiring a reduced caloric intake - this because these substances seem to prolong gastric transit time and so produce a feeling of satiety. Our research was conducted in young growing rats; it provided confirmation of the validity of Spirulina as a protein source in terms of good weight gains by the test animals and freedom from adverse effects; the same research, on the other hand, failed to confirm the effectiveness of these protein materials in reducing caloric intake: throughout the test period, indeed, feed consumption (hence caloric intake) was practically the same in the control lot and in animals receiving Spirulina protein.