Inourstudy,wetestedtheinterestofFouriertransforminfrared(FTIR)spectroscopyappliedtobileasa new diagnostic tool for differentiating patients with malignant bile duct strictures from those with benign biliary diseases. FTIR spectroscopy is based on the principle that chemical functional groups present in the studied sample absorb infrared radiation at wavelengths that correspond specifically to transitions in molecular vibrational states. It is a powerful analytical tool sensitive to changes in molecular compositions and structures, both qualitatively and quantitatively. In previous works, we and others have shown the potential of vibrational spectroscopy coupled with chemometrics methods for detecting disease-specific spectralsignatures in the serum [26–29], tears [30], urine [31], saliva [32] and cerebrospinal fluid [33]. Here, weappliedforthefirsttimehigh-throughputtransmission FTIR spectroscopy to bile samples. Since tumor cells develop in the biliary tract, tumoral markers are expected to be present in higher concentration in bile thaninblood.Vibrationalspectroscopyhaspreviously been applied to analyze intermolecular associations in bile acids reference standards [34] but, to our knowledge, it has never been evaluated as a tool for the diagnosis of bile duct malignant tumor.