Background: Breast cancer is the most frequent malignant disease amongst young women. We have observed during our study and it is also reported by other Asian studies that breast carcinoma is amongst the leading malignancies in the region and the patients are at least a decade younger than counterparts in developed nations. Age is an important issue in effective screening, diagnosis and management of breast cancer, especially in this geographical region where late presentation and poor prognosis are a hallmark of the disease. Primary objective of this study is to determine the frequency and risk factor of breast cancer in young females (age≤40years).Secondary to verify whether breast cancer patients aged less than 40 years at diagnosis have poorer prognosis than older patients. Materials and Methods: This is a retrospective study conducted at the GHaem Hospital. Descriptive and pathology data of malignant breast tumors 1388 to 1392 werereviewed, using the GHaem Hospital archived data. It included only female patients in any age. Results: Out of the 704 female breast cancer patients, 166 (23.6%) were ≤40 years. The mean age was 34.27±5.4 years among younger patients compared to 53.74±9.9 for those> 40 years. The mean age at menarche was in two group equal (p<0.99). Family history of breast cancer was evident in 0.72% of the young women versus 0.63% in the older one. At diagnosis, the mean tumor diameter was not significantly different (3.41±1.64 vs 3.71±1.40 cm, p=0.131). Axillary lymph nodes were positive in 66.3% of younger patients and 68.4% of older patients. In the younger group, the proportion of stage III or IV disease was not significantly different (54.8% vs 57.4%, p=0.284). The proportion of breast conserving surgery was higher in young patients (30.1% vs 17.8%, p=0.001) .The most common histological type was ductal carcinoma (95.2% vs 94.8%). Conclusion : These results indicate that age at diagnosis has no independent effect on clinical outcome of breast cancer. We demonstrate that tumor characteristics are the only relevant factors when deciding on disease management and treatment intensity. As breast cancer in Iran occurs at earlier age, there is a need to reevaluate the current priority given to breast cancer as a health problem in Iran.