Ionising radiation (IR) has been extensively used as therapy and diagnostic modality to detect abnormalities inside a human body. Interaction between IR and cells can lead to production of free radicals. This study aims to evaluate radioprotective properties of 50% watermelon juice against low dose ionising radiation (LDIR)-induced stress in mice lung and liver tissues following 14 days of juice supplementation. Eighteen (18) ICR mice were randomly divided into three groups, negative control (Cx), radiation (Rx) and treatment group (Tx). The Cx group was treated with normal diet and filtered water while the Rx group was given a normal diet, filtered water and irradiated with 100 µGy x-ray; Tx group was fed a normal diet, 50% watermelon juice and irradiated with 100 µGy x-ray. After 14 days, level of superoxide dismutase (SOD), reduced glutathione (GSH) and malondialdehyde (MDA) in lung and liver tissues were evaluated. The SOD inhibition activity revealed a significant decrease in Rx and Tx compared with Cx (p<0.001). The Rx and Tx showed significant reduction in GSH level compared with Cx (p<0.001) respectively. The MDA levels for lung tissues revealed a statistically significant value between Tx and Cx (p<0.05). The results suggest that 14 days supplementation of 50% watermelon juice was insufficient to foster radioprotective properties against LDIR-induced stress.