Nutritional zinc deficiency leads to immune dysfunction and aggravates inflammation. The number of white blood cells (WBCs) and platelets increases as part of the inflammatory response and may aggravate inflammation due to viral or bacterial infections. We elucidated whether the effects of zinc deficiency on blood indices were related to the inflammatory response. Five-week-old male Sprague-Dawley rats were fed a zinc-deficient diet (without zinc additives) or a standard diet (containing 0.01% zinc) for 6 weeks. The mean body weight in the zinc-deficient group decreased compared to the standard group. The mean value of the serum malondialdehyde concentration in the zinc-deficient group was higher than that in the standard group. Furthermore, serum total superoxide dismutase (SOD) and Cu/ Zn-SOD activities in the zinc-deficient group were lower than those in the standard group. The numbers of WBCs and platelets in the zinc-deficient group were higher than those in the standard group. These findings indicate that the inflammatory response, and concurrently WBC and platelet numbers, was increased after 6 weeks of zinc deficiency. Augmentation of the inflammatory response may have involved infiltration of bacteria and viruses from dermatitis, as well as changes in the balance between zinc and copper in the blood, which inhibited the antioxidant enzymes Cu/Zn-SOD, ultimately resulting in the accumulation of reactive oxygen species.