The effect of dietary tansy ragwort (Senecio jacobaea,), a plant containing pyrrolizidine alkaloid (PA), on mineral metabolism in rats was studied. In experiment 1, rats were fed a dietary level of 5% tansy ragwort. At intervals of 1, 2, 4, 6, and 8 wks animals were killed and tissue mineral levels determined. As compared to comparable controls, rats fed tansy ragwort showed by 6 wk elevated liver and spleen copper levels, and a trend to increased iron levels. Experiment 2 was a 3 × 4 factorial experiment with added dietary copper levels of 0, 50, and 250 ppm, and tansy ragwort levels of 1, 1, 2.5, and 5%. Liver copper levels increased markedly with increasing levels of tansy ragwort and supplemental copper; at 0, 50, and 250 ppm added copper, liver copper levels were 4, 18, and 21 times greater in rats fed 5% tansy ragwort as compared to those with no tansy ragwort. Increases in spleen copper were noted with 5% tansy ragwort and supplemental copper. Higher liver copper levels were observed when a casein‐based diet rather than a soybean‐meal diet was used, suggesting an effect of phytate in soybean meal in reducing copper absorption. In the last experiment,59Fe was administered to rats fed diets with or without tansy ragwort. After 5 wk on tansy ragwort, rats showed very low levels of59Fe in erythrocytes, tibia, and liver, and elevated levels in the spleen, suggesting either an impairment of hematopoesis or accelerated erythrocyte destruction as a result of PA consumption. These results indicate that PAs cause increased liver copper content and cause disturbances in iron metabolism.