In the previous work, we described the modifier of mdg4 gene and obtained one mutation in the locus designated as mod (mdg4). Here we tried to obtain new alleles of this gene participating in transcription control of mdg4. P-M hybrid dysgenesis and EMS treatment failed to give mutations. On the other hand, one strain containing mod (mdg4) 1u1 mutation spontaneously became unstable. In this strain, four novel mod (mdg4) alleles with different phenotypes have been obtained. The mutation obtained seem to be the regulatory ones.