An in vitro preparation of complete brain is presented which allows successful tracing with fast axonal tracers for at least 2 days after in vitro preparation. A simple procedure is used, by which the isolated brain is submerged in oxygenated artificial cerebrospinal fluid, enabling maintenance of adequate integrity without perfusion the vascular system. The use of an isolated brain has many advantages: virtually all brain areas are easily accessible; tracer applications are possible without problems of animal survival; and the tracers are be translocated by blood circulation. The viability of this isolated brain preparation was validated by successful recording of extracellular field potentials 1 day later.