Extraction of p-aminophenol by trialkylamine, trialkylphosphine oxide, di(2-ethylhexyl)phosphoric acid, and the mixed solvent of trialkylamine + trialkylphosphine oxide in heptane was studied under initial pH values ranging from 3 to 10. Trialkylamine and trialkylphosphine oxide extractants extracted the neutral form of p-aminophenol. Di(2-ethylhexyl)phosphoric acid extracted both neutral and positive forms of p-aminophenol. When the initial pH value was between pK(a1) and pK(a2), a maximum distribution coefficient occurred. This pH dependence can be explained by the variation of the molar fraction of neutral p-aminophenol with pH value. The mixed solvent consisting of trialkylamine + trialkylphosphine oxide had a higher distribution coefficient than the sum of those of trialkylamine and trialkylphosphine oxide; that is, there was a synergistic effect when extracting p-aminophenol with the mixed solvent.