It was tested if responses of geniculo-cortical relay (GCR-) cells in rat dorsal lateral geniculate nucleus (dLGN) to diffuse light flashes contain features permitting a separation of the cell population into slow and fast cells like the response latency to stimulation of optic chiasm (OX-latency). The location of neurons within the dLGN found additional consideration. Using hierarchical cluster analysis two clusters were obtained for on- as well as off-like neurons, which reflected to a high degree the classification into slow and fast cells by OX-latency. Two subgroups were detected in the cluster of slow cells. Multivariate discriminance analysis made it possible to separate the cell population into two classes. The latency of primary excitation to flash (primary inhibition for off-cells), the number of impulses in the first excitation peak (duration of inhibitory period) and the location of the cells within the dLGN were suited for this separation differing in 11 up to 17% from that achieved by OX-latency classification.