An overall comparative view of the analytical methods for hydrocarbon type and structural group (CHn n = 0-3) analysis of middle distillate fuels is presented. The inadequacy of traditional ASTM methods (e.g. n-d-M D3238, FIA D1319, MS D3239 and D2425) associated with the inability to relate the fuel composition to combustion performance has provided an incentive to use alternative techniques. This incentive will increase as conventional crude quality decreases and synthetic crudes become more widely used, HPLC. GC-MS and NMR techniques have emerged not only as essential tools for research but also in routine use for an excellent characterization of fuel composition-ignition quality relationships. The characterization of diesel fuel aromatic fractions by 1H NMR and GC-MS is discussed in detail.