After gel electrophoresis, quantification of in-gel fluorescence is sometimes used to assay the macromolecules fractionated. Both procedures and equipment that have the following improvements are presented here for direct video fluorometry of gels used for electrophoresis: comparatively low cost, high ease of use and low consumption of space. This equipment has a linear response to the amount of ethidium-stained DNA that forms a band in an agarose gel.