Abstract 1. 1. An in vivo microscopy technique is described for observing the microcirculation in the crop of the anesthetized Japanese quail. 2. 2. The preparation allows visualization and quantitation of changes in luminal diameters of arterioles and venules in the crop using light or fluorescent microscopy techniques. 3. 3. Responses of the microcirculation to topically or systemically administered drugs can be observed from both the mucosal and serosal sides of the crop. 4. 4. This preparation allows observation of the circulation of secretory glands in the wall of the avian crop.