Recovery of macrobenthic animal communities was determined 7 weeks after a 5-week exposure to 55 micrograms per liter pentachlorophenol. The communities developed from planktonic larvae in aquaria containing clean sand and continuously flowing estuarine water. Significantly fewer individuals and species occurred in contaminated aquaria than in control aquaria immediately after exposure to pentachlorophenol. Numbers of arthropods, chordates, echinoderms, and mollusks were decreased; annelids and coelenterates were not affected. Seven weeks after exposure was discontinued, and with continued input of estuarine water, the communities showed various degrees of recovery, carry-over effects, and changes unrelated to exposure.