This is a report of an investigation whose aim was to correlate psychological and physiological data observed during psycho-analytical treatment. The patient chosen for this study was characterized by the fact that fluctuations in his emotional state tended to evoke quite obvious physiological effects. Urine volume, creatinine content, urinary 17-hydroxycorticoid and uropepsin determinations were carried out on daily 24-hour collections of urine. Review of the clinical material suggested that the biochemical findings corresponded roughly to phases of the transference. For example, unconscious transference resistance in the early phase of the analysis corresponded to rapid fluctuations in the level of 17-hydroxycorticoid. The effect of the investigation upon the patient's transference phantasies was given special consideration.