Two experiments with 96 crossbred pigs each were conducted to study the effectiveness of Co to reduce tissue Cu accumulation in pigs. A 2 x 3 factorial arrangement of treatments, two levels of Cu (15 and 280 mg/kg) and three levels of added Co (0, 150 and 300 mg/kg), was used in both experiments. The initial body weight was 8.2 kg in experiment 1 and 7.2 kg in experiment 2. Tissue samples were taken at d 35 of experiment 1 and d 14 and d 28 of experiment 2 for mineral analysis. Cobalt failed to alleviate Cu deposition in the liver and brain at both dietary Cu levels and increased (P≤0.05) Cu deposition in the liver of the 150 mg/kg Co group. In contrast, increasing dietary Co linearly decreased (P≤0.05) Cu deposition in the kidney and Zn deposition in the liver. High dietary Cu increased (P≤0.05) serum Cu concentration and Cu deposition in the liver, brain and kidney. Copper feeding stimulated (P≤0.05) growth only during the first week in experiment 1. Dietary supplementation of 150 and 300 mg/kg of Co greatly depressed (P≤0.05) feed consumption and reduced growth rate (P≤0.05). In summary, the Cu-Co antagonism is tissue specific and could not be used to prevent liver or brain C u accumulation. In addition, the Co tolerance level for weaning pigs is lower than 150 mg/kg.