Various factors could play a role in a patient's decision to leave treatment. This study asks whether patients who leave treatment before one year are different from those who stay beyond a year in open-ended psychoanalytic psychotherapy, using a variety of experiential measures. Our data indicate that the personality trait of “openness” assessed at intake, correlates with staying in therapy, and that relationship factors as assessed by the patients during therapy correlate with staying in therapy at the beginning, at the average point of dropping out (before one year – average 31 weeks), and at the end of the study. These results indicate that the failure to engage in the therapeutic relationship is a salient factor in the phenomena of leaving before one year. Significant reductions in physical symptoms and other positive trends toward improvement do not emerge until such therapeutic engagement has occurred. We conclude that the personality trait of “openness,” and the quality of the therapeutic relationship significantly influence who will stay in open-ended psychoanalytic psychotherapy and who will go. Those who stay in psychoanalytic psychotherapy beyond one year benefit more from the experience than those who leave. Copyright © 2012 John Wiley & Sons, Ltd.