MA 16/C is a spontaneous mouse mammary adenocarcinoma. It is hormone-dependent and was injected s.c. into C3H/He female mice on day 0. Tumors were excised on day 15. Neo-adjuvant treatments were applied from day 1 to day 21 for hormonotherapy and immunotherapy and on days 1, 5 and 9 for chemotherapy. Adjuvant treatments were applied from day 21 to day 42 for hormonotherapy and immunotherapy, and on days 21, 25 and 29 for chemotherapy. Mixed (neo-adjuvant and adjuvant) treatments combined the two patterns. Chemotherapy consisted of an oxalato-platinum complex of trans-l-dach (l-OHP) at a dose of 5 mg/kg i.p. Hormonotherapy consisted of the LH-RH agonist (D-Trp6) LH-RH, at a dose of 100 micrograms/kg i.p. Zinc gluconate (6mg/kg per os) and bestatin (6mg/kg per os) were administered as immunoregulators. Under present experimental conditions, surgery alone did not increase the life span. Both neo-adjuvant and adjuvant chemotherapy and neo-adjuvant hormonotherapy, however, when added to surgery, increased survival significantly (p less than 0.02-p less than 0.03).