This study explores analytically-trained psychotherapists' experiences of uncertainty in their work with patients. Three experienced analysts were interviewed for the study: one Jungian analyst, one Freudian psychoanalyst, and one relational psychoanalyst originally trained as an ego psychologist. The analysts were asked a series of questions that explored the experiences, feelings, thoughts, sensations, changes, and images that they associate with uncertainty in their clinical work. Through phenomenological data analysis of the interviews, uncertainty was revealed to be an important and inevitable experience for the analysts that is both challenging and enriching and that impacts them inside and outside their consulting rooms. The implications of the findings are considered for both psychotherapists and laymen, and the study applies the findings to the research process itself. The study also includes an extensive review of the existing literature on clinical uncertainty. The electronic copy of this thesis is on a single disc containing a single PDF file which can be opened with Adobe Acrobat Reader.