Time-averaged human electroretinogram (ERG) responsesswere determined for several workplace visualsstimuli which are temporally modulated at rates exceedingsthe perceptual critical fusion frequency (CFF).sA clearly identifiable synchronous response was insevidence for a video display terminal (VDT) stimulussoperating with a refresh rate as high as 76 Hz. A directlysviewed fluorescent luminaire with controllable drivingsfrequency elicited a synchronous response at rates asshigh as 145 Hz. In addition, an intense stimulus createdsby modulating the light from a slide projector producedsresponses at least as high as 162 Hz. The implicationssof these high-frequency responses as representing aspotential basis for visual symptoms are discussed.