Transverse sections of white birch ( Betula platyphylla ) were treated with anhydrous ammonia at 60–140°C (ammonia treatment, AT). As a result, the crystal structure of cellulose in the AT samples changed to cellulose III I , and acetamide was produced. The surface area of the AT samples, the amount of sugar released upon acid hydrolysis and the lignin content were not changed. However, a small amount of lignin became acid soluble. Mäule color reaction, indicative of the presence of syringyl lignin, showed decreasing color intensities with increasing temperature of AT. The results can be easily interpreted that AT affects ester linkages and side chains of hemicelluloses and syringyl lignin. In addition, AT was carried out on 1-μm thick transverse sections and block specimens. Xylanase treatment and immunolabeling revealed that AT enhances xylan degradation, but ray cells are resistant to xylanase even after AT. On the block sample, a deposited xylan layer appeared on the inner surface of fiber cell walls. Apparently, xylan moved to the surface in contact with the fluid ammonia during AT. The vessel cell wall did not show a similar migration effect, indicating a cell wall-specific interaction with ammonia.