GATA1 is one of the most fascinating transcription factors for biologists. It regulates many haematopoietic genes and interacts with a number of other transcription factors. Its functions are mostly conserved among vertebrates. Upon disruption of the GATA1 gene, mice show a drastic bloodless phenotype. GATA1 knockdown mice are predisposed to tumour development, the extent of which varies depending on the level of knockdown. When GATA1 is overexpressed, certain cells face an altered cell fate. These observations suggest the importance of regulation on the expression level and timing of GATA1. Deciphering such regulation is the key to understanding the commitment and differentiation of blood cells. There are so many splendid reviews describing GATA1 as a transcription factor. We therefore focus our topics on GATA1 gene regulation in this review.