Tables 2 and 3 and Figs. 1–3 show the test results for the samples. All the examined properties were found to be highly (P < 0.01) affected by the RW–kenaf ratio used. These effects were further analyzed by the least significant difference method and the results are presented in Table 3. Fig. 1 illustrates the effects of RW–kenaf ratio on the MOR values of the three-layer particleboards. The three-layer particleboards which consist of kenaf stem in the middle layer had higher strengths than the three-layer panels with kenaf core in the middle. Type 1 panels exhibited the highest MOR value of 15.74 N/mm2. This suggests that panels with 70% RW particles had as much high as 23% increment in MOR in comparison with the panels with 30% RW particles within the surface layers. On the other hand, it was found that the strengths of Type 1 panels were enhanced by 38% more than the strengths of Type 8 panels which were manufactured of 100% KC.