The data on 262 patients with minimal breast cancer (less than 1 cm in diameter) are presented. The long-term results of treatment of this group were good: 5- and 10-year survival rates were 91.2 and 79.5%, respectively. However, minimal breast cancer tended to produce regional (28.5%) and distant (10.3%) metastases. Organ-saving operation, viz. lumpectomy en bloc with axillary-subclavian adipose tissue was frequently (18.5%) followed by local and regional recurrence development. Adjuvant thiotepa therapy caused a 17.8% decrease in the frequency of recurrence and distant metastases development.