The epidermal growth factor receptor (EGFR) and its ligands are involved in cancer pathogenesis and they might serve as circulating biomarkers. The current study aims to investigate if abnormal pre-treatment serum levels of EGFR and EGFR ligands are present in women with early-stage breast cancer and if up- or downregulation of EGFR and EGFR ligands occur in defined patient subgroups. Pre-treatment serum samples were obtained from 311 women with newly diagnosed early-stage breast cancer and from 419 healthy women and analysed for EGFR and the ligands: Epidermal growth factor (EGF), heparin-binding epidermal growth factor (HBEGF), betacellulin (BTC), amphiregulin (AREG), and transforming growth factor α (TGF-α). Previously, age-dependent 95% reference intervals for EGFR and the EGFR ligands have been established based on the healthy women population. S-EGFR, S-EGF, S-HBEGF, S-AREG, and S-TGFα were all significantly different in women with breast cancer compared to healthy women (p < 0.05). Elevated S-EGFR, according to the reference intervals, was present in 11.3% of breast cancer patients, whereas decreased S-EGF was found in 11.6%. Elevated S-EGFR was associated with estrogen receptor positivity of tumor (ER+) and a subgroup of ER + breast cancer patients showed markedly elevated S-EGFR (>120 ng/mL).