Objective To compare molecular subtypes of breast cancer in the youth and elderly.Method 61 cases of youth patients（youth group）and 58 cases of elderly patients（elderly group）with breast cancer received in the department of Breast Surgery of the Affiliated Hospital of Guiyang Medical College were detected estrogen receptor（ER）

human epidermal growth factor receptor（HER-2）

progesterone receptor（PR）and Ki-67 expression with the method of Immunohistochemical Envision to classify breast cancer into four subtypes

namely Luminal A type

Luminal B type

HER-2over-expression type and triple-negative type

and analyze their distribution.Results In the elderly group

Luminal A type

Luminal B type

HER-2over-expression type and triple-negative type were respectively 46.6%

37.9%

8.6% and 6.9%

while in the youth were 23.0%

39.3%

18.0% and 19.7%.Elderly patients had higher incidence of Luminal A type than the youth patients and the difference was statistically significant（P<0.05）.Conclusions The breast cancer molecular in elderly patients is mainly Luminal A type with a better prognosis

youth patients are more vulnerable to have HER-2over-expression and triple-negative types and breast cancer of the youth is much worse than that of the elderly.