Abstract: Extracts of garlic and/or Platycladus orientalis were applied on Coprinus comatus during cultivation to determine theireffects in inhibitingpathogenic growths,whileat the same time, promoting mushroom development.Size of inhibitory areaon petri disheswas observed to compare the efficacies ofmicrobial inhibitionby the extracts. Whereas, mycelial growth and fruit body yield weremonitored for the direct effect of the extracts on the mushroom development. The results showed that by mixing the twoextracts ofgarlic and P. orientalis, awiderantimicrobial spectrumcould be realizedas compared towhen they were used separately. A7:3 mixing ratio of the garlic:P. orientalis extracts produced a superior resultin providing aconsistent inhibitory effect against 3pathogens. Specifically, the extractsobtained from a 6 h-extraction was highly effective on Penicillium spp. and Rhizopus spp.,with thecontrol rates of 38.46%-62.85% and 57.98%-67.74%, respectively.pH of the mixesdid not seem to be a significant factoronthe pathogenicinhibition. Nor was mycelial growth significantly affected by application of the extracts. On the other hand, the mushroom yield increasedsignificantly as compared to control. Insofar as the length of processing timeis concerned, the 12 h-extraction rendered a product with the greatest increase(i.e., 168.59%); while,the 48-, 6-, and 24 h-extractionsresulted in 72.63%, 65.72%, and 57.17%yield increases, respectively, incomparison to control. In addition,by using the mixed extracts in cultivation, the time required between harvests could be shortened andthecap/stem ratio of thefruiting body increased, thereby, mushroom production efficiency could be improved and costreduced over the conventional operation.