Coniferous woods were modeled as honeycomb cellular solids consisting of hexagonal-prism tracheids to examine the mechanism for radial compression. Because of the abrupt breaks of radial cell walls, it was assumed that the flrst break followed Euler's equation of buckling. The nominal stress at the buckling of the radial cell wall was theoretically obtained based on this assumption, and the actual nominal stress was obtained experimentally. The theoretical stress was found to correspond almost to the experimental value. This finding suggests that the abrupt first break that occurs in wood under radial compression can be mainly attributed to the buckling of radial cell walls.