OBJECTIVE: To determine the prevalence and co-occurrence of common geriatric syndromes in geriatric rehabilitation inpatients. DESIGN: Restoring Health of Acutely Unwell Adults (RESORT) and Enhancing Muscle Power in Geriatric Rehabilitation (EMPOWER-GR) are observational, longitudinal cohorts. SETTING: Geriatric rehabilitation. PARTICIPANTS: Geriatric rehabilitation inpatients (N=1890 and N=200). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Geriatric syndromes included polypharmacy, multimorbidity (Cumulative Illness Rating Scale), cognitive impairment, depression (Hospital Anxiety and Depression Scale/Geriatric Depression Scale), malnutrition (Global Leadership Initiative on Malnutrition), functional limitation (Katz index), falls, physical frailty (Fried), and sarcopenia (European Working Group on Sarcopenia in Older People 2). RESULTS: Inpatients in RESORT (R) (N=1890, 56% females) had a median age of 83.4 years (interquartile range [IQR], 77.6-88.4) and in EMPOWER-GR (E) (N=200, 57% females) of 79.8 years (IQR, 75.0-85.9). Polypharmacy (R, 82.2%; E, 84.0%), multimorbidity (R, 90.4%; E, 85.5%), functional limitation (R, 96.0%; E, 76.5%), and frailty (R, 91.8%; E, 92.2%) were most prevalent. Most inpatients had ≥5 geriatric syndromes at admission in both cohorts (R, 70.0%; E, 72.4%); few inpatients had only 1 (R, 0.4%; E, 1.5%) or no geriatric syndrome (R, 0.2%; E, 0.0%). Geriatric syndromes did not occur in isolation (without other syndromes), except for multimorbidity (R, 1%; E, 5%), functional limitation (R, 3%; E, 2%), falls (R, 0%; E, 4%), and frailty (R, 2%; E, 5%), which occurred in isolation in some inpatients; sarcopenia did not. CONCLUSIONS: Geriatric syndromes are highly prevalent at admission to geriatric rehabilitation, with a median of 5 co-occurring syndromes. Implications for diagnosis and intervention potential should be further addressed.