From a sample of 265 elderly subjects (age 80.2 +/- 6.8 years) admitted to a geriatric care unit, free from cardiac and respiratory diseases, with normal chest X-ray and gas analysis, 53 subjects were selected and their respiratory functions (assessed by spirometric parameters and airway resistance 'Raw') were studied to correlate them with nutritional status, cognitive impairment, independence in everyday life activities and mood disorders, assessed, respectively, by the Mini Nutritional Assessment, rapid Mini Mental State test (MMSr), activities of daily living (ADL), instrumental activities of daily living (IADL) evaluation, Barthel Index and Cornell Depression Scale. The enrolled subjects were able to perform normally a forced expiration, although most of them committed errors in this test, according to the American Thoracic Society (ATS) criteria. Thus, about 32% started at lung volume<total lung capacity while about 82% started too slowly (i.e. time to PEF>0.12 s); in 62% of the subjects expiration time was too short and in 58% the terminal plateau was <2 s. Nevertheless, the spirometric parameters (and Raw) were considered normal. Forced vital capacity and peak expiratory flow (but not FEV1) were higher in the subjects without disability, while cognitive and nutritional status did not seem to have any influence on spirometric performance; MMSr score was related to compliance with ATS criteria for acceptability of the forced manoeuvre; mental and mood disorders, nutritional conditions and disability did not seem to have any influence on error rates. Our data show that our geriatric enrolled patients were able to perform an imperfect, often unfinished, but acceptable forced expiration; dynamic index values were related to disability, while the errors in starting the test were related to the mental conditions.