This study demonstrates subtle differences in psychological states of patients in two different coronary care units. In comparing the emotional states and medical course of patients on the two units, the net advantage of the “open unit” seems to be in providing more social contact with associated freedom of expression of hostile feelings, while the lack of privacy resulted in higher levels of “shame anxiety”. The “closed unit”, on the other hand, provided privacy at the expense of human interactions, resulting in increased feelings of loneliness and a displacement of hostile feelings. Certain individual patients may do much better in one or the other type of environment. It is hoped that with further study, it may be possible to identify the characteristics of patients who might be suited to a particular type of C.C.U. Better still, an ideal coronary care unit could be designed, combining the best of both possible worlds, where both “togetherness” and privacy are provided for the patients. The association found in this and other studies between affective states and the incidence of serious medical complications underline the need to take the patients' emotional welfare into account in the design and staffing of the hospital environment.