Six-week-old female BALB/c mice were inoculated with 2 × 104 PFUs of the influenza A/WSN/33(H1N1) virus, after receiving Spirulina extract 4 hours prior to infection by oral gavage. Spirulina extract was again administered at 6 hours post-infection and twice daily thereafter for 4 days, at respective daily doses of 10, 25, or 50 mg/kg. Survival rates were improved in mice treated with Spirulina extract, as compared to vehicle-treated controls that did not receive Spirulina extract. Statistical analyses of the survival curves were performed using the Log-rank (Mantel-Cox) test compared each Spirulina extract treated group to the vehicle-treated group (n = 5 mice per group). *P < 0.05, **P < 0.01.