Elevated CO2 and ozone were found to influence the growth and allocation of  extraradical ectomycorrhizal mycelia (ERM) in Aspen by using 30μm mesh bags.  The study took place at the FACTII FACE site near Rhinelander, WI.  Mesh bags were collected at 296, 366 and 447 days after being buried to a depth of 10 cm.  We found that significant CO2 and O3 main effects were evident with elevated CO2 demonstrating a 54 % increase in ERM, while elevated O3 showed a 40 % decline.  Fumigation with CO2 was found to dampen the O3 effect where ERM production was decreased under the CO2 x O3 treatment by 8 % compared to 60 % for O3 by itself.  Only a slight increase in ERM was evident with elevated CO2.  C-mineralization of hyphae demonstrates a significant CO2 effect with both treatments mineralizing mycelia at a faster rate than ambient or O3 grown mycelia.  Nitrogen content of the mycelia was also influenced by the treatments with ambient averaging 2.1 % while the fumigation treatments demonstrated a reduced N content.  The implications of these fumigation effects will be discussed.