Ganoderma lucidum (Reishi mushroom), the object of our experiments, is also known to contain medicinal compounds. This fungus has been used for many centuries as medicine in China. The fruiting body of the fungus contains carbohydrates, amino acids, little protein, fat, alkaloids, vitamins and minerals. Two groups of its substances are reported to be effective particularly. One of them is constituted by the polysaccharides, whose antitumor and immunostimulating effects are well demonstrated, and the other is constituted by the triterpenes. The latter include ganoderic acids, ganolucidic acids and lucideric acids. These acids have been reported to suppress liver hyperactivity (Lelley 1999). The experiment was carried out with 8 Reishi mushroom strains in 3 repetitions. Experiments were performed on 3 different substrates The spawn run period took approximately 2 weeks, the first fruiting bodies appeared on the 33rd day from inoculation, but the formation of the fruiting bodies took almost 70 days on the different substrates. Spawn run presented a diversified picture as influenced by the specific substrates. No spawn run was seen with any of the strains on the substrate composed of 100% wheat straw. Among the strains the fastest spawn run was produced by GA02 and GA06. The earliest start of spawn run was registered for substrate 1 after 1 week.