The Monokaryotic isolates of two strains collected from two different strains 'SH' and 'MS of P. ostreatus were used to estimate the compatibility of matings. They were crossed in all combinations and dikaryon formation was assayed by the presence of clamp connections. All 134 dikaryotic F1 hybrids were obtained out of 144 monokaryotic crosses derived from two parent strains. The growth and density of the F1 hybrid mycelia differed considerably and the morphological characteristics of mycelial colony of F1 hybrids varied from cottony, feathery, puffy to streak. When the 12 monokaryons of 'SH' crossed with 12 monokaryons of 'MS', 122 strains were capable of normal fruiting and 12 were not fruited among 134 strains tested indicating 91% success rate. The reason for failure of fruiting body formation in 12 combinations may be not because of the incompatibility of mating types but unfavorable environmental condition for fruiting initiation and development. The pileus of F1 hybrids were varied with funnel 68.0%, hemispherical 25.4%, plane 6.6% in the shape and gray 59.8%, blue 35.3%, white 3.3%, brown 1.6% in the color.