Vaccines prepared from whole, killed organisms (pertussis and possibly influenza) may cause neurological allergic reactions producing encephalopathy. Vaccines prepared from live-attenuated viruses (measles, mumps, rubella, and trivalent oral poliovirus) can cause symptomatic viral infection of the nervous system, including measles encephalitis, which occurs in 1 of 1,000,000 vaccine recipients; rubella neuritis, in less than 1 of 10,000 recipients; and paralytic poliomyelitis, in 1 of 3,000,000 vaccine recipients or their close contacts. The most common neurological disorders associated with various vaccines, and offer suggestions aiming at a better understanding if a causal relationship between the neurological complications and the vaccination is feasible. Neurological complications following vaccination are rare, and in most cases, represent a monophasic neurological event with good clinical recovery. However, serious and fatal complications have been reported. In general, neurological adverse events may not be causally related to the vaccine, and occur at much lower rates than same events following natural disease. The relationship between vaccinations and the onset of serious neuropsychiatric diseases is certainly one of coincidence rather than causality. In modern society, a potentially serious adverse event attributed to a vaccination is likely to be snapped up by the media, particularly newspapers and television, as it appeals to the emotions of the public.