The AHI1 gene is involved in axons crossing the midline during development, and its mutation can cause Joubert syndrome and other related neurological system diseases. Its transcriptional regulation mechanism is still unknown. Here we cloned and characterized the upstream 5' region of the gene. It was shown that 1.3 kb upstream of ATG had the transcription activity. Progressive deletion analysis was done, and all the constructs were transfected into COS7 cells. The promoter activity was determined by fluorescence microscopy, flow cytometry, and reverse transcription polymerase chain reaction. Our results showed that all the constructs had transcription activity. The highest promoter activity was 30 bp upstream of ATG, which included a transcription factor-binding site for Oct-1. Our research provides an important basis for further investigations on the transcriptional regulation of the human AHI1 gene.