Objectives: To compare the clinicopathological features of breast cancer in two distinct patient populations below and above age of 40 and to investigate whether it is associated with a more aggressive tumor biology and disease progression in young female patients. Methods: A retrospective study conducted at the oncology clinic at King Hussein Medical Center. A total of 90 females with histopathology proven invasive breast cancer aged less than 40 years (group A) were matched with a group of 160 female patients whose age was 40 years or older (group B) during the period of 2007 to 2014. Demographic variables collected included age, mode of presentation, details of radiological imaging. Data reviewed from the histopathology report included tumor histology, site, size, grade, lymphovascular invasion, perineural invasion, number of lymph nodes involved by the tumor, hormonal status of tumors. Recurrence and site of distant metastasis were obtained during regular follow-up. Results: The median age was 35 years (range 24-39 years) in Group A and 55 years (range 40-75 years) in Group B, The median duration of symptoms was longer among patients in group A. Patients in group A had larger tumors, more lymph nodes involved by tumor, higher stage at presentation, more estrogen negative tumor, and more patients developed distant metastasis or local recurrence during follow up. Conclusions: Breast cancer in young patients is associated with more advanced disease, more aggressive histopatholgy and biological characteristics, higher rate of recurrence and distant metastasis.