Purpose: To analyze the long-term effects of exposure to low-dose γ-irradiation on sur- vival and life span in directly irradiated Daphnia magna and their offspring. Materials and methods: One-day-old Daphnia magna were exposed to 10, 100 and 1000 mGy of acute γ-rays. The life-span of irradiated and control animals, as well as their non-exposed progeny was analyzed. Results: Irradiation at dose of 100 and 1000 mGy resulted in a significant decrease in the life span of irradiated Daphnia. The data presented here also show that the survival of non-exposed first-generation offspring of irradiated parents is significantly compromised, thus implying the presence of transgenerational effects. Conclusion: The results of our study show that low-dose irradiation significantly reduces the life-span of directly exposed Daphnia and their first-generation offspring. The observed compro- mised viability is most likely attributed to non-targeted effects of ionizing radiation.