Purpose: To introduce the scanning laser ophthalmoscope-evoked mfERG (SLO-mfERG) as a new method to measure focal retinal function. Methods: Sixty-two healthy individuals and 12 patients with Best's disease were examined. mfERGs were recorded using a scanning laser ophthalmoscope as a stimulator and trigger device (He-Neon 632.8 nm) as well as a fundus-monitoring system (infrared 730 nm). Results: Amplitudes in the central concentric area were found to be significantly lower in patients with Best's disease than in healthy controls, while no significant differences were found for the more peripheral areas. Conclusion: SLO-mfERG is a reliable new technique for topographic mapping of retinal function under simultaneous control of fixation.