We have developed a simplified method for the preparation of liver nuclear extracts to study gene regulation and protein-DNA interactions. This protocol uses conventional laboratory equipment and standard reagents. The liver tissue is homogenized in a low-salt solution at physiological molarity with subsequent adjustment of the molarity and purification of nuclei by density sedimentation. The nuclear extracts are transcriptionally active in a validated cell-free transcription assay and contain functional DNA-binding proteins. This protocol results in the rapid preparation of highly reproducible and active liver nuclear extracts.