Introduction People with COPD have cognitive dysfunction, which is greater in those hospitalised for exacerbations than in stable outpatients [Dodd et al Chest 144:119-27]. Aims We tested the hypothesis that cognitive dysfunction is a disease-specific feature of COPD exacerbations by comparing cognition in patients hospitalised with COPD exacerbations or with worsening heart failure. Methods Patients hospitalised with COPD exacerbations or congestive or left sided heart failure (HF) without previous stroke, neurological disease or alcohol dependence completed the Montreal Cognitive Assessment (MoCA), Hospital Anxiety and Depression score (HAD) and underwent spirometry and review of clinical records. Results Age, acute illness severity and comorbidities were similar in COPD and HF. Table 1. Patient characteristics COPD HF P value Age (years) 73±10 76±11 0.422 Gender (% male) 40 70 0.057 APACHE II 15.4±3.5 15.9±3.0 0.628 Charlson Index 2.3±1.9 2.6±1.5 0.588 Pack years 51±35 11±16 <0.001 FEV 1 :FVC (%) 56±14 71±16 0.024 MoCA was lower in COPD (21.0±5.8) than in HF (24.9±3.6, p=0.013). Visuospatial/executive function (COPD 2.7±1.5; HF 3.9±1.3, p=0.008) and attention (COPD 3.8±1.7; HF 5.0±1.3, p=0.014) were impaired in COPD and anxiety and depression (HAD. COPD 19.6±9.8; HF 13.9±7.5, p=0.045) were increased. On multiple linear regression, HAD (p=0.01), pack years (p=0.033) and age (p=0.008), but not primary diagnosis (COPD/HF) or gender, were independently associated with MoCA. Conclusions Hospitalised COPD patients with exacerbations have greater cognitive impairment than those with worsening heart failure. Differences may be explained by greater smoking load and more anxiety and depression.