The investigations included adult female blue foxes and their offspring at a fox farm. The diet for carnivorous fur animals was improved with a synthetic antioxidant to protect feed components. The influence of a chosen antioxidant on some reproductive traits and performance parameters was determined. The antioxidant dose introduced to a feed (Rendox) proved to benefit the animal health status. The females from the basic herd that received the antioxidant showed higher reproductive parame-ters as well as higher body weight at slaughter. Besides, the animals were positively scored at the licence (conformation) evaluation as compared to the females from the control group.