Breast cancer classifies to 4 major subgroups according to immunohistochemistry staining features as Luminal A, Luminal B, human epidermal growth factor receptor 2 overexpression, and Triple Negative. Cancer Antigen15-3 (CA15-3) is used as a tumor marker in breast cancer while its value in early stage and in breast cancer subgroups is still controversial. In this study, we aimed to investigate that whether it is or not differences of the serum preoperative CA15-3 levels in early breast cancer subgroups. We retrospectively investigated medical records of 751 breast cancer patients who admitted to Afyon Kocatepe University Department of Medical Oncology between January 2010 and December 2016. Total 361 patients were included in this study. The cut off value of Ki-67 was used as 20 to distinguish between Luminal A from Luminal B subgroups. Cutoff values of CA15-3 were evaluated as 25U/mL. CA15-3 levels were not significantly different according to clinical features. Molecular subgroups were similar in CA15-3 levels (P = 0.666). Elevated levels of CA15-3 ≥ 25 U/mL were found 34 patients (20.5%) in Luminal A, 15 patients (28.3%) in Luminal B1, 15 patients (20.3%) in Luminal B2, 7 patients (25%) in human epidermal growth factor receptor 2 overexpressed and 9 patients (22.5%) in triple negative groups. There was no relationship preoperative CA15-3 levels and breast cancer subgroups.