The natural history of breast cancer is complex and the treatment modalities need to be adjusted to this heterogeneous disease. Several prognostic indicators have been described for breast cancer, including the extent of axillary nodal metastasis, the size of the primary tumor mass, various histopathologic characteristics, estrogen and progesterone receptor content, tumor proliferation index, detection of oncogenes, tumor suppressor genes, loss of heterozygosity, and growth factors. Although no single parameter or combination of parameters can definitively predict the outcome of the disease, combined criteria such as tumor estrogen receptor content, cell proliferative index, and lymph node status are relevant for identifying subsets of breast cancer patients that may require different therapeutic modalities. Detection of oncogenes, tumor suppressor genes, and growth factors need further evaluation to determine their usefulness as prognostic factors.