The efficacy of monoethanolamine and sodium bisulfite pulping black liquors at three concentrations of 1, 1.5 and 2% on the preservation of poplar wood from white rot (Trametes versicolor) was investigated. The wood specimens were impregnated with the black liquors using a full-cell method. The black liquors enhanced the decay resistance without any reduction in mechanical strength, and a remarkable increase was observed at higher concentrations and weight gain percentage. The performance of monoethanolamine black liquor was more pronounced, probably due to lower kappa number and higher pH. The durability class of specimens impregnated with 2% monoethanolamine and sodium bisulfite black liquors improved from 5 (not durable) to 1 (very durable), and from 5 to 3 (moderately durable), respectively. Chemical analysis showed that the presence of additional lignin in wood alters the white rot. Results of anatomical studies showed that the fibers of the control and impregnated wood specimens were collapsed after 16 weeks of incubation. Leaching tests confirmed that the fixation of black liquors in wood should be examined for further studies.