By laboratory evaluation, the resistance of ammoniacal copper borate (ACB)-treated wood to termites and decay fungi was excellent. The retention required to prevent biodegradation was not greatly different from ammoniacal copper arsenate (ACA). Although results of the ongoing field tests will be needed for verification, it appears that ACB could quite satisfactorily replace ACA for ground contact exposure of preservativetreated wood. Recommendation of ACB for aboveground exposure does not seem premature. -- AATA