This study was aimed to find factors responsible for export potential of oyster mushroom through postharvest treatments including high pressure CO₂ and anti-moisture pad. Temperature fluctuation during export simulation induced the condensation of excess moisture resulting in the quality loss due to browning and decay. Anti-moisture pad was effective on inhibition of browning occurrence in part. High temperature exposure (15 oC) as retail simulation greatly offset the positive effect of anti-moisture pad. Short term treatment of high pressure CO₂ delayed the surface color changes as hunter L, a, and b values. There was no consistent tendency in total sugar and phenolics between treatments. In general, the export potential of small size mushroom (export size) at harvest was higher than large ones (domestic size). The major factors associated with the quality decrease of oyster mushroom during export were moisture condensation in packages and temperature fluctuation. Further research is required to improve mushroom export procedures.