Background: Epidermal growth factor receptor (EGFR) inhibitors are being used to treat malignancies originating from epithelia. Unfortunately, blocking the EGFR pathway leads to various side effects, most frequently acneiform eruptions. Objective: To probe the mechanism underlying this side effect, we investigated the effect of EGFR inhibitors on cultured sebocytes. Methods: To examine the effects of an EGFR inhibitor (cetuximab, Erbitux Ⓡ 10 ng/ml) and the effects of EGFR ligands, such as epidermal growth factor (EGF, 10 ng/ml) and transforming growth factor-α (TGF-α, 5 ng/ml), on the production of inflammatory cytokines in cultured sebocytes, we used reverse transcriptase-polymerase chain reaction, immunocytofluorescence and Western blots. Outcomes included the expression of interleukin (IL)-1, IL-6, tumor necrosis factor-α (TNF-α), peroxisome proliferator-activated receptor-γ (PPAR-γ) and EGFR. Results: There were no significant differences in the expression of IL-1, IL-6, TNF-α, PPAR-γ and EGFR between (a) groups treated with an EGFR inhibitor or an EGFR ligand and (b) the control group, except for a significant increase in the expression of IL-1 in the EGF-treated group. Conclusion: EGFR inhibitors and EGFR ligands do not provoke the expression of inflammatory biomarkers in cultured sebocytes. The role of the sebaceous glands in EGFR inhibitor-induced acneiform eruption should be investigated more thoroughly. (Ann Dermatol 23(1) 12∼18, 2011)