SUMMARYSix diploids ofAspergillus parasiticusinvolving 12 genetic markers were analyzed by means of the parasexual cycle. Heterokaryotic heads consisted of homokaryotic and heterokaryotic conidial chains. Due to the intra-conidial complementation between spore-color mutants, heterokaryotic spores were green (wild-type). Gene action for spore-color determination was autonomous. The analysis of two mutants impaired in aflatoxin production revealed the independent segregation of genes involved in the biosynthesis of aflatoxin. Loci for four auxotrophs, one spore-color mutant, and two aflatoxin mutants were assigned to four linkage groups.