Experimental panels of conventional tongue-and-groove flooring lumber of 5 different wood species were dip-treated for 3 minutes in a 5 percent, light-oil solution of pentachlorophenol, then exposed off the ground in 3 diverse climates. Limited amounts of decay 22 to 23 years later evidenced continuing protection on all sites. Bioassay and x-ray spectrometric analysis of panels in western Oregon, where decay control was greatest, indicated that penta was still present in small amounts. -- AATA