Long-term breathlessness is more common with age. However, in the oldest old (>85years), little is known about the prevalence, or impact of breathlessness. We estimated breathlessness limiting exertion prevalence and explored (i) associated characteristics; and (ii) whether breathlessness limiting exertion explains clinical and social/functional outcomes. Health and socio-demographic characteristics were extracted from the Newcastle 85+ Study cohort. Phase 1 (baseline) and follow-up data (18months, Phase 2; 36months, Phase 3; 60months, Phase 4 after baseline) were examined using descriptive statistics and cross-sectional regression models. Eight hundred seventeen participants provided baseline breathlessness data (38.2% men; mean 84.5years; SD 0.4). The proportions with any limitation of exertion, or severe limitation by breathlessness were 23% (95% confidence intervals (CIs) 20-25%) and 9% (95%CIs 7-11%) at baseline; 20% (16-25%) and 5% (3-8%) at Phase 4. Having more co-morbidities (odds ratio (OR) 1.34, 1.18-1.54; P< 0.001), or self-reported respiratory (OR 1.88, 1.25-2.82; P= 0.003) or cardiovascular disease (OR 2.38, 1.58-3.58; P< 0.001) were associated with breathlessness limiting exertion. Breathlessness severely limiting exertion was associated with poorer self-rated health (OR 0.50, 029-0.86; P = 0.012), depression (beta-coefficient 0.11, P = 0.001), increased primary care contacts (beta-co-efficient 0.13, P = 0.001) and number of nights in hospital (OR 1.81; 1.02-3.20; P = 0.042). Breathlessness limiting exertion appears to become less prevalent over time due to death or withdrawal of participants with cardio-respiratory illness. Breathlessness severely limiting exertion had a wide range of service utilisation and wellbeing impacts.