Toll-like Receptor 4 (TLR4) recognizes endogenous ligands which are released following organ injury. TLR4^-/- mice develop diminished left ventricular hypertrophy after transverse aortic constriction (TAC). We analyzed whether pharmacologic TLR4 antagonism with Eritoran tetrasodium equally reduces cardiac hypertrophy in C57BL/6 mice. A catheter was implanted into the jugular vein for repeated Eritoran tetrasodium (5mg/kg body weight; Esai Inc., Endover, MA USA) or placebo application. 3 days after TAC or sham surgery heart weights were determined, and cardiac tissue was prepared for RNA and protein quantification. The TAC placebo group exhibited a significant increase of left ventricular weight (LVW) compared to sham and TAC Eritoran tetrasodium groups. TAC placebo mice differed significantly in heart weight, LVW/tibia length as well as LVW/body weight ratio compared to all other groups. B-type natriuretic peptide mRNA was elevated significantly only in TAC placebo mice. TAC surgery led to a distinct increase of IL-1b and IL-6 mRNA and protein expression in the placebo compared to the TAC Eritoran tetrasodium group. MMP-9 zymographic activity was highest in the TAC-placebo animals. Thus, the pharmacological antagonism of TLR4 with Eritoran tetrasodium prevents the development of cardiac hypertrophy in a murine 3 day TAC model.