The aim of the present investigation was to study peroxidase activity in different subcellular fractions of thyroid and oviduct and to ascertain whether there is any difference between the two sexes of peroxidase activity of the thyroid gland or between the thyroid and oviduct of a wild avian species, the tree pie (Dendrocitta vagabunda). Peroxidase activity was maximum in the soluble supernatant fraction of both the tissues with acetate buffer at pH 5.5, but the enzyme activity was highest even in low concentration of the substrate (H2O2) in the thyroid gland. Thiourea, thiouracil and azide inhibited enzyme activity in both thyroid and oviduct. While ascorbic acid inhibited peroxidase activity in the thyroid gland, it stimulated in the oviduct. Moreover, the enzyme activity was maximally inhibited by ascorbic acid in the thyroid and by thiourea in the oviduct. Peroxidase activity was highest with NAD+ in the thyroid and cytochrome C in the oviduct. Peroxidase activity was higher in females. It is suggested that avian thyroid/oviduct peroxidase activity may differ somewhat from that of mammals and possibly also in the peroxidase activity between the thyroid and oviduct of the tree pie.