The neurotoxic effect following a single intraperitoneal injection of MK-801 (10 mg/kg) in adult female Wistar rats at different survival times was studied with the 1994 version of de Olmos' Amino-Cupric-Silver (A-Cu-Ag) technique for detection of neural degeneration. In addition to the well documented somatodendritic degeneration observable in cortical olfactory structures, dentate gyrus, retrosplenial and sensory cortices, we detected this type of neuronal degeneration also in the main olfactory bulb, motor and anterior cingulate cortices, thalamus and cerebellum. Terminal degeneration, not reported by previous authors, was detected in cortical olfactory structures, hippocampal formation, sensory, infralimbic, prelimbic, agranular insular, ectorhinal, perirhinal and lateral orbital cortices. These results demonstrate that the A-Cu-Ag procedure is more efficient than other silver methods for detecting the degeneration induced by MK-801. In fact, the use of the A-Cu-Ag method has made it possible to infer the connectional relations between the damaged cell bodies and corresponding terminal degeneration. Our results also indicate that the A-Cu-Ag technique may be a suitable method for the staining of neurons undergoing apoptotic-like degeneration. The probable degenerative mechanism of MK-801 in the main olfactory system is discussed.