Methyl bromide (MB) is a widely used fumigant in most of the countries for quarantine purpose. However, MB has been phasing out and under control in many countries because it is listed as an ozone-depleting substance under the Montreal Protocol. In this study, we have investigated the effectiveness of phosphine fumigation on wood pests for developing an MB alternatives. We evaluated two bioassay methods; wooden cube (10×10×10 cm) and normal fumigation procedures in comparison with effectiveness of phosphine (PH3) penetrations into the timber block. Fumigation to adults of Reticulitermes speratus was carried in a desiccator system for 24hr at 5 and 15 ℃. As a result, LC99 of PH3 to R. speratus in wooden cubes and insect breeding dish at 5℃ was 0.183 and 0.177 mg L-1, respectively. LC99 of PH3 in wooden cubes and insect breeding dish at 15℃ was 0.077 and 0.078 mg L-1, respectively.