The cis-acting element in the promoter of the rat ATP-citrate lyase (ACL) and transcription factors which interact with these elements were determined. Six Sp1 binding sites and CAAT box exist in the region from transcription start site to -419 bp which showed the highest promoter activity in ACL promoter previously. In the region from -612 to -419, C/EBP binding site and other protein binding sites were also detected. Chloramphenicol acetyltransferase assay of ACL promoter suggested that multiple Sp1 sites might be involved in the ACL transcription. Gel mobility shift assay with antibodies against Sp1 and Sp3 revealed that DNA binding efficiency of Sp1 is increased in the liver of rats re-fed low fat/high carbohydrate diet after fasting. These results suggest that Sp1 is one of the most important transcription factors for ACL promoter to produce basal and induced transcription by low fat/high carbohydrate diet.