Surface-active trace compounds present in diesel fuels protect pumps and injectors against premature wear through boundary lubrication. Due to the vast number of hydrocarbon compounds found in petroleum distillate fuels, it is difficult to measure the concentration of trace lubricity-enhancing compounds in neat diesel fuel samples. We report herein the direct measurement of trace polycyclic aromatic hydrocarbons (PAH) in diesel fuels through H-1 and C-13 nuclear magnetic resonance spectroscopy and relate the presence of PAH with fuel lubricity measured with a high-frequency reciprocating rig. Carboxylic acids and nitrogen heterocyclic PAH were not detected in the diesel fuels tested. The data provide further evidence that surface-active PAR compounds improve the lubricity of diesel fuels.