The first of the new generation of meteorological advanced sounders, The Atmospheric Infrared Sounder (AIRS) was launched in 2002. AIRS was able to provide hyperspectral data for operational and research use. The improved spectral resolution it provided compared to earlier passive infrared sounders, led to a significant increase in vertical resolution and accuracy in determining thermal and moisture fields. The first assimilation trials to use full spatial resolution and higher spectral resolution hyperspectral radiance data, available in real time from the AIRS are reviewed here. The results from these assimilation trials was significant improvement in forecast skill in the National Centers for Environmental Prediction (NCEP) Global Data Assimilation System (GDAS), compared to the global system without AIRS data over both the northern and southern hemispheres. A second trial was an experiment which showed the advantage of using all AIRS fields of view (fov) in the analysis as opposed to the use of sampled fields of view (typically one-in-eighteen) often used by Numerical Weather Prediction (NWP) Centers. Another trial showed the benefit of using hyperspectral data with expanded spectral coverage. In addition beneficial impact has been seen in recent experiments where radiances, derived from cloudy AIRS fields of view (fovs) and which represent the radiance emanating from the clear part of the cloudy fov, have been assimilated for global NWP. This impact is an initial indication of the potential benefit of using cloudy hyperspectral radiances routinely in global NWP. Generally it has been demonstrated that a more complete use of the information content in the observations available from hyperspectral sounders has resulted in improved benefits to NWP. This conclusion is also supported by early experiments reporting the benefits from using IASI data. Overall, the results indicate the significant benefits to be derived from hyperspectral data assimilation and importantly the benefits yet to be gained from an enhanced use of the information content contained in hyperspectral radiance observations.