Tec is a cytoplasmic protein-tyrosine kinase highly expressed in hematopoietic precursor cells. To investigate the mechanism regulating its expression, we cloned and characterized the mouse tec promoter. The promoter region does not contain the authentic TATA or CAAT box but has several consensus binding motifs for GATA and SP1. The nucleotide sequence surrounding the major transcription initiation site determined 5' RACE-PCR appeared to be homologous to the "initiator" consensus sequence which is frequently found in genes lacking TATA and CAAT. The promoter activity of the 5' flanking region was confirmed by using the luciferase assay. The present analysis will provide insights into the mechanism for the expression and regulation of the Tec molecule.