We have previously reported effects on breast carcinoma by digitalis on patients in vivo with significant effects on cytometric features and recurrence rate. Increased attention is now paid to the anti-proliferative and apoptosis inducing effect on cancer cells in vitro by glycosides from foxglove as well as by some other glycosides. The present study is a long-term follow-up (22.3 years) of 175 patients with breast carcinoma, of which 32 were on digitalis treatment, when they acquired their breast carcinoma. There was a lower death rate (6%) from breast carcinoma among the patients on digitalis, when compared with patients not on digitalis (34%). Also proliferation/aneuploidy was less pronounced of the tumors in patients on digitalis. These observations were statistically significant although the statistical analysis was hampered in the life-table analysis by the fact that only 2/32 patients on digitalis died from breast cancer. Serious consideration should be given to the effects of digitalis derivatives on cancer cells in cancer drug design. This field of research is not sufficiently explored and holds promise to contain drugs superior to present-day adjuvant therapy both with respect to effects and side-effects.