•Frail elderly COVID-19 patients showed frequent extrapulmonary signs and symptoms.•Frailty, dehydration and mechanical ventilation predicted mortality in the elderly.•Secondary infections and metabolic complications should be considered in the elderly. The spectrum of COVID-19 clinical manifestations is not yet known. In the elderly, mortality and extrapulmonary involvement appears more frequent than expected. A multicentre-retrospective-case-series study of COVID-19 patients, aged ≥65 years, hospitalised between March 1 and June 15, 2020. Patients were classified at admission into 3 groups based on their Clinical Frailty Scale (CFS) score: 1–3 (group A), 4–6 (group B) and 7–9 (group C). Of the 206 patients in the study, 60 (29%) were assigned to group A, 60 (29%) to B and 86 (42%) to C. Significantly more frequent in group C than in B or A were: mental confusion (respectively 65%, 33%, 7%; P < 0.001), kidney failure (39%, 22%, 20%; P = 0.019), dehydration syndrome (55%, 27%, 13%; P < 0.001), electrolyte imbalance (54%, 32%, 25%; P = 0.001), and diabetic decompensation (22%, 12%, 7%; P = 0.026). Crude mortality was 27%. By multivariate logistic regression model independent predictors of death were male sex (adjusted odds ratio (aOR) = 2.87,95%CI = 1.15–7.18), CFS 7–9 (aOR = 9.97,95%CI = 1.82–52.99), dehydration at admission (aOR = 4.27,95%CI = 1.72–10.57) and non-invasive/invasive ventilation (aOR = 4.88,95%CI = 1.94–12.26). Elderly patients with a high CFS showed frequent extrapulmonary signs at admission, even in the absence of lung involvement. These findings, along with a high CFS, predicted a significant risk of mortality.