The structures of atmospheric-pressure, fuel-rich, premixed benzene-air flames have been described by the concentration profiles of reactants and also major and minor combustion products, as measured along the axes of two benzene/air flames with different C/O ratios (0.72 and 0.77). The main effect of the C/O ratio was on the flame temperature and on the final yields of CO, C2H2, polycyclic aromatic hydrocarbons (PAHs), and soot, whereas the relative distributions of the light hydrocarbons and PAHs did not change on increasing the C/O ratio. Large amounts of phenol and cyclopentadiene were found early on in the flames. Acetylene and methane were the dominant hydrocarbon products and had much larger concentrations later on than the C-3-C-4 unsaturated hydrocarbons. PAHs were formed within the main reaction zone and were rapidly destroyed, while soot was formed. Some small differences in the distribution of PAHs were found with an aliphatic fuel. The concentration of PAHs as evaluated by gas chromatography takes into account a very small amount of condensed species, which are formed in significant quantities at soot inception and then consumed while soot is formed.