There is an expectation that intermediate care services for older people will be widely introduced in England. The planning of such services should be based on an understanding of required capacity. The present study provides a needs estimate for post-acute intermediate care. Older patients admitted acutely to an elderly care department in a district general hospital serving a large city in northern England were followed prospectively by a research team until medical stability had occurred in the opinion of the senior ward nurses and the responsible consultant. The clinical staff then determined if the patient had continuing post-acute care needs or if imminent discharge was possible. Out of 1211 acutely admitted patients, 997 became medically stable and 312 [25.8% of admissions; 95% confidence interval (CI) = 23.3-28.2%] were considered to require post-acute care, and of these, 251 (20.7% of admissions; 95% CI = 18.4-23.0%) needed post-acute rehabilitation care. In conclusion, the present authors suggest that intermediate care services providing post-acute care for older people should have a capacity to address the needs of up to one-quarter of acute admissions to a district general hospital elderly care department.