Descriptions of visionary experience from written medieval sources are examined from a cross-cultural perspective. The mental states of the persons having the visions range from terminal illnesses, states of starvation, stress-related syndromes, dreams and hypnagogic states, and seemingly unremarkable mental states. Although a few of the visions elicited some skepticism on the part of contemporaries, most reports of visions were accepted at face value as bona fide visions, with no discernible differentiation between starvation visions, dreams, deliria of illnesses, and possible mental illness. Only four of the visions appeared causally related, by today's standards, to mentally illnesses. These persons were not recognized as mentally ill by their contemporaries. Since there was a recognition of mental illness in the Middle Ages, it would appear that such recognition was based on symptoms other than visions or hallucinations. It is also possible that hallucinations, as culturally supported phenomena, were not as available as forms of expression of psychoses in the Middle Ages as they are today. Such a possibility has interesting implications regarding the role of a culture in shaping the forms by which mental illnesses are expressed, recognized, and labeled.