Despite continually increasing evidence for the effectiveness of psychodynamic psychotherapy in general, the empirical status of long-term psychodynamic psychotherapy (LTPP) remains controversial. Convincing outcome studies of LTPP were lacking for a long time. This article gives an overview of available systematic reviews addressing the evidence for LTPP. The findings suggest that LTPP can yield large and stable effects across a variety of diagnoses and particularly in complex mental disorders, which even tend to increase after termination of treatment. In comparison to other shorter or less intensive methods of psychotherapy, LTPP has proven to be significantly superior with respect to most outcome domains. First economic analyses suggest that LTPP may be cost-effective in the long run. The comparison of randomized controlled with observational studies revealed no significant differences in outcome; however, the evidence for LTPP is frequently challenged by proponents of other therapeutic approaches or scientific orientations. The criticisms were repeatedly answered and none of the concerns raised by critics identified an issue that would have affected the overall conclusions of the available reviews. Nevertheless, further studies are urgently required to broaden the evidence base for LTPP in order to allow more refined analyses addressing the effects of specific forms of LTPP both in specific disorders and in comparison to specific forms of alternative therapies.