Despite the fact that malaria is an extraordinarily common condition and cerebral manifestations of malaria occur in about 2% of cases, little scientific attention has been focused on the psychic effects of malarial infestation. One important reason for the dearth of data on the psychopathological concomitants of malaria is the failure to obtain routinely thick blood smears on patients admitted to psychiatric units in areas in which malaria is endemic and on the steadily increasing numbers of patients recently returned from such areas. In this paper the author reviews published data on the incidence of cerebral malaria, its neurological and psychiatric manifestations, and the pathophysiology of the condition. With these data as background, the author reports the comparatively high incidence of acute psychotic episodes associated with malaria among patients admitted during a 2-year period to the only psychiatric facility in Liberia, West Africa. The clinical characteristics of these patients are described and illustrated by 4 case examples. Drawing on these clinical observations, the three following questions are considered: 1) Can environmental stress precipitate an attack of malaria? 2) Can environmental stress plus malaria precipitate a psychotic episode? and 3) Can malaria alone precipitate an acute exacerbation of chronic mental illness?