In the present study, we investigated the genetic basis of mushroom cap color. In first generation hybrids between a brown isolate and the white commercial hybrid U 1, the white trait was recessive. Color was determined using color meter technology in second generation hybrids obtained by crossing the homokaryotic progeny of a first generation hybrid with a homokaryon from U 1. Statistical analysis revealed a bimodal distribution describing two classes of white and not-white hybrids. We postulate that a recessive allele at a single locus (PPC1) encodes the white pilei-pellis color. Joint segregation analyses indicated thatPPC1was linked to theADH(alcohol dehydrogenase) locus. Through the analysis of the heterokaryotic progeny of the first generation hybrid, a recombination model is proposed in whichPPC1is located between the centromere and theADHlocus.