In this study, gizzard erosion was investigated in twelve 4-5 weeks old chickens. The mortality rate was determined as 7 per cent. Grossly, erosions with varying sizes and numbers were found in the affected gizzards. Histologically, the normal, homogenous appearance of koilin lining was altered into vacuoles. Koilin layer was thickened in some areas and eroded in others. In these areas, desquamation of epithelial cells, infiltrations of inflammatory cells and erythrocytes into the koilin layer were seen. In the underlying, degeneration, desquamation and sometimes necrosis of the gland epithelium could be observed. Inflammatory reactions, such as heterophils and light mononuclear cell infiltrations, were detected in the lamina propria of gizzard.