Stress is a complex phenomenon and exposure to stress results in a series of reactions in the organism, including alterations in behaviour and various physiological changes. Role of nutrition in the maintenance of homeostatic mechanisms, including the stress, is very dense. The current study aimed to evaluate the potential effects of Spirulina ( Arthrospira ) platensis against mix stress models. For this purpose, 36 Sprague-Dawley male rats were allocated into four groups; 1. Control(C), 2. Stress(S), 3. S.platensis (Sp) and 4. S. platensis + Stress (SpS). S. platensis was applied to Sp and SpS groups by oral gavage (1500 mg/kg/day) for 28 days. All rats were exposed to light : dark cycle (long lightening period; 18h light : 6h dark) stress for 14 days. Also, S and SpS groups were stressed with additional mix stress by leaving in crowded environment and hosting alone under long lightening period. The animals which fed with S. platensis , shown significant changes in the numbers of circulating leukocytes, % of n eutrophils, and the n eutrophil : l ymphocyte ratio. However, there were no significant differences in the morphological parameters. In conclusion, the possible preventive effect of S. platensis on hematological parameters was shown in a rat’s stress model of social stress which was included mix stress under long lightening period.