Background: Patients undergoing radiotherapy may suffer from many harmful effects including gut microbiota injury, therefore, the use of exogenous probiotics is suggested to reduce these effects. Aim: The present study aimed to determine the possible protective effect of Spirulina platensis and Chlorella vulgaris against radiation-induced hematological and biochemical disturbances in male albino rats. Materials and Methods: Spirulina or chlorella was administered orally at a dose level of 300 mg/kg body weight daily for one week before and one week after the exposure to gamma radiation (6Gy, single dose). Results: Whole-body gamma-irradiation induced a significant decrease in total leukocyte count, red blood cell count, hemoglobin concentration, hematocrit value and platelets count, compared to their corresponding values of the control group. A significant increase in alanine aminotransferase (ALT) activity, marker of liver damage, and a non-significant increase in urea and creatinine levels, markers of kidney function was is observed. Spirulina or chlorella administration pre- and post-irradiation has significantly attenuated the radiation-induced disturbances in the studied parameters. Conclusion: oral supplementation of spirulina or chlorella may afford protection against radiation-induced detrimental effect and may preserve the tissue integrity and the functions of different organs in the body.