In conclusion the effects of aeration through lid hole filters on the hyphal growth of Lentinula edodes in sawdust cultivation bags were investigated. An appropriate ventilation hole size and position for the mushroom hyphal growth was 15 mm on underside of the lid. Conventional cotton plugs can be effective for mycelial growth, ventilation of carbon dioxide and controlling water loss from the bags. The greater the hole size on the lid of the cultivation bags, the greater the water loss from the medium. However, mycelial growth was not proportional to the ventilation hole size, but rather to carbon dioxide production. Thus, the appropriate ventilation hole size for the greatest mycelial growth in the bags should be determined by considering gas diffusion and water evaporation from the bags.