Aims: This study was conducted to determine the antioxidant capacity, immunomodulatory and lipid-lowering effects of spirulina in healthy elderly subjects and to document the effectiveness of spirulina as a functional food for the elderly. Methods: A randomized double-blind, placebo-controlled study was performed. The subjects were 78 individuals aged 60–87 years and were randomly assigned in a blinded fashion to receive either spirulina or placebo. The elderly were instructed to consume the spirulina or placebo at home, 8 g/day, for 16 consecutive weeks. Results: In male subjects, a significant plasma cholesterol-lowering effect was observed after the spirulina intervention (p < 0.05). Spirulina supplementation resulted in a significant rise in plasma interleukin (IL)-2 concentration, and a significant reduction in IL-6 concentration. A significant time-by-treatment intervention for total antioxidant status was observed between spirulina and placebo groups (p < 0.05). In female subjects, significant increases in IL-2 level and superoxide dismutase activity were observed (p < 0.05) after spirulina supplementation. There were significant reductions in total cholesterol in female subjects. Conclusions: The results demonstrate that spirulina has favorable effects on lipid profiles, immune variables, and antioxidant capacity in healthy, elderly male and female subjects and is suitable as a functional food.