The manifest contents of most phobias concern dangers coming from the environment. It is the degree of those neurotic fears rather than their objects which makes them appear unrealistic. Fears of dangers coming from outside the environment in which the patient lives, such as fear of cosmic happenings, have usually been found to be associated with schizophrenia. Recently the knowledge of our physical environment and the scope of its exploration have been undergoing fundamental changes. This has been reflected in the symptomatology of phobias. The following four patients seen in the psychiatric outpatient department of the United Sheffield Hospitals during the last eighteen months illustrate how a change in the popular concept of physical reality can produce a new type of neurotic fear. The first case is given in greater detail than the others, because the patient's power of verbalization was above average.