A flexible optical fiber probe for attenuated total reflection (ATR) spectroscopy with Fourier-transfer infrared (FT-IR) spectroscope is developed. The probe is based on a hollow optical-fiber that comprises a polycarbonate thin tube and silver-and polymer-inner layers and that shows low losses in a wide wavelength range in the infrared. The probe has an ATR prism whose shape is optimized for use with hollow optical fibers. Some results on preliminary experiments show the potential uses of the probe in clinical applications. The probe is appropriate for in-vivo applications used with a thin endoscope because the fiber comprises only non-toxic and chemically durable materials.