This study compares the results of modified radical mastectomy (144 cases) to radical mastectomy (188 cases) in the treatment of operable breast cancer. Two hundred five patients had Stage I breast cancer, 60 had Stage II disease and 67 had Stage III disease (TNM System). There was no statistically significant difference in five year survival when the results of a radical mastectomy were compared to a modified radical mastectomy at any stage of disease. There was no statistically significant difference in the incidence of local recurrence in patients with Stage I and Stage II disease when the results of a radical mastectomy were compared to modified radical mastectomy. Those patients with Stage III disease who were treated by a modified radical mastectomy had a statistically significant higher incidence of local recurrence (chest wall and axilla) in comparison to patients treated by radical mastectomy. We have concluded that a modified radical mastectomy is the treatment of choice in patients with Stage I and Stage II diseases. In patients with Stage III disease, a radical mastectomy provides a better chance of local control of the disease but offers no increased chance of survival.