In the USSR the CNS is considered to be highly sensitive to radiation. Nervous system effects are said to have been demonstrated at as low as 0.1 r; many papers discuss effects with doses of a few hundred r. However, it does not seem possible to reach a final conclusion on CNS radiosensitivity. A general critical analysis of reported Soviet experiments suggests a need for increased use of statistical analysis and controls, reporting of negative experiments, more complete documentation of findings, etc. Possible important theoretical implications are considered. These include the role of numerous random, neuronal disturbances on function; the effects of possible altered afferent activity due to stimulation of nerve fibers or receptors by radiation; alterations in nervous control of physiological activities such as bone marrow regeneration, etc. The role of the nervous system in radiation pathogenesis continues to be studied very intensively in the USSR. The major doctrines of Pavlovian "nervism" are now being applied in a somewhat less formal and apparently more circumspect way. Confirmation of a number of the cited experiments is urgently needed to fully document the lower limit of CNS radiosensitivity, both in chronic and acute exposure circumstances.