In any disease, the knowledge of the natural history of untreated cases provides a real background against which the real advantages of a new treatment itself are judged. Fortunately, in the present days, there are scant data on outcomes in patients with untreated breast cancer. In an attempt to provide this background against which the virtues of current curative and palliative treatments can be more accurately assessed, we have reviewed the literature regarding published untreated breast cancer series. Taking into consideration all the difficulties of analyzing reports written on the last half of the nineteenth century or on the first half of the twentieth century, in most reports, patients survived almost 3-4 years without any type of treatment. Worth mentioning, approximately 5-10 % of untreated patients lived longer than 10 years. Thus, the spectrum of clinical aggressiveness of untreated breast cancer varies between virulence and chronic disease. These facts should be taken into account when considering the value of current treatments for early-stage disease.