Psychoanalytic psychotherapy in clinical practice is traditionally a long-term treatment conducted by well-trained psychotherapists. However, very few studies have been published that evaluate the effects of such treatment. To redress this lack of studies, 55 individuals selected for long-term psychoanalytic psychotherapy (average, 3 years) were invited to participate in a naturalistic study. The psychotherapists had a mean of 15 years of professional experience. The 36 patients who completed psychotherapy manifested a substantial reduction in symptomatic suffering and decreased levels of character pathology, as measured by the Karolinska Psychodynamic Profile (KAPP) and the Karolinska Scales of Personality. Generally, such changes were not found in the individuals who did not engage in treatment. In the therapy group, improvements were found on eight KAPP subscales defining different aspects of character: Intimacy and Reciprocity, Frustration Tolerance, Regression in the Service of the Ego, Coping with Aggressive Affects, Conceptions of Bodily Appearance and their Significance for Self-esteem, Sexual Function, Sexual Satisfaction, and Personality Organization. The results indicate that individuals who engaged in psychotherapy improved their capacity to handle crucial aspects of life and reduced their symptomatic suffering.