In recent taxonomic works albinism is not generally recognized as being present in the Agaricales. This study was made to find how albinism was inherited in Psilocybe mutans McKnight. Cultures of P. mutans were incubated in a constant temperature room at 20-22°C. With artificial lighting at 150 foot candles for 16 hours per day and on a laboratory bench at a comparable temperature with diffuse natural light of a lesser intensity. Numerous fruit-bodies were obtained from cultures which grew on substrates containing hot water extracts of rabbit fecal pellets and from cultures grown on substates containing no fecal extracts. In the mating test cultures which did not fruit were examined for clamp connections in the contact zone, Clamp connections were found in two of the crosses. This was taken as evidednce that these crosses were made with common B heterokeryons. In the above mating test fruit-bodies were produced only on the mycelial mats growing only from one of the strains. Three of the cultures were examined for the distribution of clamp connections and it was found that the clamp connections were associated only with the fruiting mycelial mat. This was taken as evidence of unilateral dikaryotisation.