Summary Background: Recovery from anaesthesia is a high risk period for horses. Arterial hypoxaemia is common during anaesthesia, likely exacerbated during recovery when oxygen supplementation is challenging, and may impact on recovery quality, although this is under-investigated. Objectives: To evaluate if hypoxaemia during recovery from anaesthesia has a negative impact on recovery quality and identify factors likely to impact on arterial oxygen tension (PaO ₂) during this time. Study design: Prospective observational clinical cohort study. Methods: One hundred and two systemically healthy adult horses recovering from inhalational general anaesthesia were studied. Arterial blood samples were obtained anaerobically at end of anaesthesia (T), immediately following positioning in the recovery box (R0), when horses achieved sternal recumbency (S0) and immediately upon standing (STAND). Data were analysed using backward stepwise multivariable logistic regression (influence of cofounding factors on PaO ₂) and receiver operating characteristic curve analysis (association between PaO ₂ and recovery quality). Significance was set at P<0.05. Results: Presence of arterial hypoxaemia (PaO ₂ <60mmHg) at any of the four time points investigated did not impact on recovery quality. Factors associated with PaO ₂ at R0 were body weight, ventilation strategy and change of recumbency between surgery and recovery ( P<0.001). PaO ₂ at time points T, R0, S0 and STAND was not found to be predictive of recovery quality. Conclusions: Body weight, ventilation strategy and change of recumbency between surgery and recovery are cofounding factors for PaO ₂ at R0. It is not possible to predict recovery quality from PaO ₂ during recovery.