The objectives of the study were: a) to isolate, identify, and determine the relative frequency of the principal decay and other wood-inhabiting fungi associated with decay development at the groundline zone, b) to determine the frequency and extent of decay in poles as affected by time in service, and c) to determine the effects of additional factors such as pole size, checking patterns, preservative treatment, and soil type on the frequency and extent of decay. A total of 890 poles were sampled from a total population of approximately 20,000 Douglas-fir treated poles. Poles were selected to represent service ages in yearly increments from zero (storage yard) to 10 years and diameter classes ranging from 14 to 26 inches at the groundline. The pole lines were divided into five geographic regions. -- AATA