The nsdD gene has been predicted to encode a GATA type transcription factor with the type IVb zinc finger DNA binding domain functions in activating sexual development of A. nidulans. In several allelic mutants of nsdD producing truncated NsdD polypeptides lacking the C-terminal zinc finger, the transcription level of nsdD gene was greatly increased. Also in an over-expressed mutant, the transcription under its own promoter was reduced. These results suggest that the expression of nsdD is negatively autoregulated. When the nsdD gene was over-expressed, cleistothecia were formed in excess amounts even in the presence of 0.6 M KC1 that inhibited sexual development of the wild type. Northern blot analysis revealed that the expression of nsdD was repressed by 0.6 M KC1. These results strongly suggest that the inhibition of sexual development by salts was carried out via the nsdD involved regulatory network.