Cyanobacteria Spirulina maxima from Texcoco Lake in Mexico was administered as a 5% component of a purified diet, to Wistar rats together with a high percentage of fructose (60%) and its effect on several lipid fractions of plasma and liver was studied and compared to those of rats fed purified diets containing 60% of glucose or 60% of fructose. A preventive effect of Spirulina maxima on the fructose-induced increase of the liver triglycerides level was observed together with an elevation of the phospholipid concentration in this tissue. On the other hand Spirulina maxima produced a plasma cholesterol level even lower than that observed in the control group.