Breast cancer is the most common malignancy in females all over the word. It represents about 34% of total malignancies among IRAQI females with high mortality rate representing 1-2% of female mortality &16% of cancer deaths in females in IRAQ. Many prognostic factors which can affect the treatment outcome have been studied to identify patients at high risk of disease relapse who might benefit from post-operative adjuvant therapy. The Aim of this study was evaluation of different prognostic factors to drive a reliable (Prognostic Index) that best fits our breast cancer patients, hoping to give the adjuvant treatment accordingly. This is a study analysis of 566 female patient treated for primary breast cancer between 1992 and 2001 at Oncology Unit, Marjan teaching Hospital. Modified prognostic index (PI.). Was used to identify different prognostic group. We could divide patients into 4 groups : Group 1 with PI <2.5, group 2 with PI > with PI >2.5-3,group 3 with PI>3-3.5 and group 4 with PI>3.5. The 5 year overall survival (OS) and relapse free survival (RFS) were calculated for the whole group and for the different 4 prognostic groups as well as for influence of systemic adjuvant treatment. The 5 year O.S and RES were 75% and 55% respectively for patient with PI< 2.5 and decreased with the increase of the value of PI to reach 50% and 10% respectively in patients with PI> 3.5. The difference in both 5 year O.S, RFS for different prognostic groups was found statistically significant only between patients with PI<3. (Groups 1&2) and those with PI>3. (Groups 3 &4) with P < 0.001. It was shown those patients with PI<3 could benefit from the addition of adjuvant system treatment with better 5 year RFS of 60% in comparison to 40% for patients who did not receive adjuvant systemic treatment (P=0.01). Minimal benefit was obtained in – patients with PI > 3. It was concluded that more intensive adjuvant treatment my be warranted for group 3 and 4 of patients