Five isolates of Neurospora spp. were collected from soil in central and northern Iraq. Species were identified according to their fertility when crossed with authentic strains. However, ambiguous results caused difficulties in exact identification. Esterase activities in Iraqi isolates and reference strains were analysed in order to provide additional criteria for identification. In spite of the genetic variabilities observed between local and tester strains as well as between conidial and mycelial contents of esterase isozymes, this biochemical method could be used together with crossing behavior in species identification.