According to several literature surveys women with three consecutive and clinically ascertained spontaneous abortions appear to have without treatment an abortion risk of 50 to 60 per cent in the course of any further pregnancy. For improving prognostication various conditions leading to habitual abortions have to be clarified before the onset of a new pregnancy. Among our patients corpus luteum dysfunctions (35 per cent) and anomalies of the uterus (17 per cent) showed the highest frequency. Our patients also had an increased frequency of pathological spermiograms. Their influence on the incidence of habitual abortions remains, however, unclear. Infectious diseases and metabolic disorders (5 per cent) as well as chromosomal aberrations (6 per cent) appeared to be less frequent. Controversial views on the consequences of blood group incompatibilities of the spouses continue to exist. Conflict-oriented personalities of patients seem to play a major role. After evaluating the findings in literature pertaining to habitual abortions and on the basis of our own results (110 patients) diagnostic and therapeutic guidelines have been worked out. By employment of the individually required therapy 90 per cent of the patients with habitual abortions were able to successfully complete a further pregnancy.