Hemp seed and flaxseed are a source of valuable substances, such as n-3 fatty acids or vitamin E, which increase the quality of products but also affect animal health. At the Institute of Animal Science, a number of experiments were performed to test different levels and ratios of these seeds in mixed feeds for laying hens and broiler chickens. To increase the performance and strength of the bones, it was appropriate to include 30 g/kg of hemp seed in the diet for laying hens. In the case of feeding both seeds simultaneously (40 g/kg of hemp seed and 60 g/kg of flaxseed), there was a positive synergistic effect on the content of n-3 fatty acids and γ-tocopherol and a negative synergistic effect on the content of cholesterol in the yolk. The addition of 40 g/kg of hemp seed together with 60 g/kg of flaxseed to the feed mixture also proved successful in broiler chickens. Feeding this combination improved chicken performance, meat quality and bone strength, and the storage of α-tocopherol in the liver. The increase in bone strength in laying hens and chickens after hemp seed administration was first described in studies based on the results of experiments performed at the Institute of Animal Science This finding may mitigate the risk of fractures in laying hens associated with the change of housing system from enriched cages to floor systems.