Can the analyst's night-dream about his patient be considered as a manifestation of countertransference—and, if so, under what conditions? In what way can such a dream represent more than just the disguised fulfilment of a repressed wish of the analyst? Is there not a risk of the analyst unconsciously taking up and ‘using’ the content of a session or other elements coming from the analytic situation for his own psychic reasons? The author, closely following Freud's dream theory, shows the mechanisms which can allow us to use the dream content in the analytical situation: preserved from the secondary processes of conscious thinking, other fantasies and affects than in the waking state can emerge in dream thought, following an ‘unconscious perception’. After examining the countertransference elements of Freud's dream, ‘Irma's injection’, which leads off The interpretation of dreams, the author presents a dream of her own about a patient and its value for understanding affects and representations which had hitherto remained unrepresented.