To investigate the expression and mutation of transcription factor GATA-2 gene in acute non-lymphocytic leukemia (ANLL), the GATA-2 gene were amplified in peripheral blood mononuclear cells from 85 cases with ANLL using RT-PCR, and the PCR products were further analyzed by single strand conformation polymorphism (SSCP) and sequencing. The results showed that GATA-2 gene was expressed in the most cases with ANLL (89.4%). One larger band was observed by RT-PCR in a case with M(1) subtype. Nucleotide sequence analysis revealed a insertion of 18 nucleotides at position 1 288 bp of the GATA-2 gene cDNA, thereby leading to 6 additional amino acids in second zinc finger complex of GATA-2, and it includes a cysteine which can bind to zinc ion. The insertional mutation may change the function of GATA-2 transcription factor. To our knowledge this is the first description of insertional mutation in the GATA-2 gene.