Comet Assay IV interactive video-based software system measures the DNA damage detected using single-cell gel electrophoresis (SCGE). A high-definition video camera attached to a microscope provides real-time cell scoring by transferring a live video image to a computer screen with no time lag. Click and Score automatic scoring mode allows all measurement parameters to be immediately calculated and recorded with a single click on the comet head. The software compensates for slides with uneven backgrounds or varying levels of brightness to ensure comparable results even when highly damaged ‘hedgehog’ comets are present. Data can be saved to Microsoft Excel or to an Oracle database if additional security is required in regulated environments. An optional Data Extractor program allows authorized users to examine and retrieve all data for use with the standard Spreadsheet Generator macro or any custom or third party data processing and reporting tools.