Funkenstein, Greenblatt, and Solomon 1 claimed that any significant alteration in a patient's mental state is invariably accompanied by a change in his physiological response to their test. Feinberg, 2 reviewing the current status of the Funkenstein test, concluded that the value of the test as an objective index of clinical change could not be assessed, as this aspect of it had not been systematically studied. It is the aim of this paper to describe an investigation in which the hypothesis that clinical improvement in hospitalized patients with depressive illnesses is associated with a change in their blood pressure response to methacholine was tested. Material and Methods Many of the investigations into the value of the Funkenstein test deal with tests done by different observers on patients with different types of illnesses. Often, too, the selection of patients is not clearly defined. In the present investigation, 25 consecutive admissions to one