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Current photochemical models developed to simulate the atmospheric degradation of aromatic hydrocarbons tend to underestimate OH radical concentrations. In order to analyse OH budgets, we performed experiments with benzene, toluene, <i>p</i>-xylene and 1,3,5-trimethylbenzene in the atmosphere simulation chamber SAPHIR. Experiments were conducted under low-NO conditions (typically 0.1–0.2 ppb) and high-NO conditions (typically 7–8 ppb), and starting concentrations of 6–250 ppb of aromatics, dependent on OH rate constants. For the OH budget analysis a steady-state approach was applied in which OH production and destruction rates (<i>P</i>_OH and <i>D</i>_OH) have to be equal. The <i>P</i>_OH were determined from measurements of HO₂, NO, HONO, and O₃ concentrations, considering OH formation by photolysis and recycling from HO₂. The <i>D</i>_OH were calculated from measurements of the OH concentrations and total OH reactivities. The OH budgets were determined from <i>D</i>_OH/<i>P</i>_OH ratios. The accuracy and reproducibility of the approach were assessed in several experiments using CO as a reference compound where an average ratio <i>D</i>_OH/<i>P</i>_OH = 1.13 ± 0.19 was obtained. In experiments with aromatics, these ratios ranged within 1.1–1.6 under low-NO conditions and 0.9–1.2 under high-NO conditions. The results indicate that OH budgets during photo-oxidation experiments with aromatics are balanced within experimental accuracies. Inclusion of a further, recently proposed OH production via HO₂ + RO₂ reactions led to improvements under low-NO conditions but the differences were small and insignificant within the experimental errors.