The author summarizes a monograph study on the course of schizophrenia into old age, which he co-authored with C. Müller, and which includes mortality and cause-of-death statistics on 1,642 original cases and an average of 37 years of catamnestic observation of the 289 patients who survived until the final followup examination. The separate investigations of the development of schizophrenia, the psycho-organic symptomatology, and the social adaptability show that the long-term course was favorable in at least half of the cases. From a statistical viewpoint, outcome depended primarily on premorbid personality factors, on certain psychopathological factors, and on the influence of advanced age. These findings supported and supplemented important findings by other authors (in particular those of Bleuler and Huber), on the long-range development of schizophrenia.