Spectroscopic sensing systems are among the most promising techniques following the recent trends towards continuously operating in-situ analytical tools. The mid-infrared spectral region considered from 2 - 20 micrometers is of particular interest, as compound-specific information based on fundamental rotational and vibrational transitions is provided. Thus, inherently selective qualitative and quantitative data can be obtained. With the development of mid-infrared transparent optical fibers, conventional spectroscopic techniques, such as Fourier transform infrared spectroscopy, can be evolved into a sensor format. The appearance of novel mid-infrared light sources, e.g. quantum cascade lasers, and the potential of microfabrication technologies, allows to significantly scale down the optical components. In combination with advanced molecular recognition schemes, such as molecularly imprinted polymers, a new generation of mid-infrared optical sensing devices can be envisaged, with applications ranging from environmental and process analysis to the biochemical/biomedical field.