A sample of Phyllostachys makinoi was investigated by analysis of its chemical composition and electron microscopic observations of the cell wall structure before and after extraction as well as degradation procedures. The quantitative determination resulted in 2.6% extractives, 25.5% lignin, 45.3% alpha-cellulose, and 24.6% pol-yoses. The main polyose is an arabinoxylan with a Xyl: Ara ratio of about 17:1. The electron micrographs show a lamellar deposition of lignin and polyoses within the secondary walls. Lignin is obviously soluble by parts in alkaline as well as in acidic reagents. Sodium hydroxyde solution removes cell wall substance mainly from the secondary walls, whereas trifluoroacetic acid removes substance from the compound middle lamellae.