Background: The rising number of older multimorbid in-patients has implications for medical care. There is a growing need for the identification of factors predicting the needs of older patients in hospital environments. Our aim was to evaluate the use of clinical and functional patient characteristics for the prediction of medical needs in older hospitalized patients. Methods: 242 in-patients (57.4% male) aged 78.4±6.4 years, who were consecutively admitted to internal medicine departments of the University Hospital Essen between July 2015 and February 2017, were prospectively enrolled. Patients were assessed upon admission using the Identification of Seniors at Risk (ISAR) screening followed by comprehensive geriatric assessment (CGA). The CGA included standardized instruments for the assessment of activities of daily living (ADL), cognition, mobility, and signs of depression upon admission. In multivariable regressions we evaluated the association of clinical patient characteristics, the ISAR score and CGA results with length of hospital stay, number of nursing hours and receiving physiotherapy as indicators for medical needs. We identified clinical characteristics and risk factors associated with higher medical needs. Results: The 242 patients spent [median(Q1;Q3)]:9.0(4.0;16.0) days in the hospital, needed 2.0(1.5;2.7) hours of nursing each day, and 34.3% received physiotherapy. In multivariable regression analyses including clinical patient characteristics, ISAR and CGA domains, the factors age (β=-0.19, 95% confidence interval (CI)=-0.66;-0.13), number of admission diagnoses (β=0.28, 95%CI=0.16;0.41), ADL impairment (B=6.66, 95%CI=3.312;10.01), and signs of depression (B=6.69, 95%CI=1.43;11.94) independently predicted length of hospital stay. ADL impairment (B=1.14, 95%CI=0.67;1.61), cognition impairment (B=0.57, 95%CI=0.07;1.07) and ISAR score (β =0.26, 95%CI=0.01;0.28) independently predicted nursing hours. The number of admission diagnoses (risk ratio (RR)=1.06, 95%CI=1.04;1.08), ADL impairment (RR=3.54, 95%CI=2.29;5.47), cognition impairment (RR=1.77, 95%CI=1.20;2.62) and signs of depression (RR=1.99, 95%CI=1.39;2.85) predicted receiving physiotherapy. Conclusion: Among older in-patients at risk for functional decline, the number of comorbidities, reduced ADL, cognition impairment and signs of depression are important predictors of length of hospital stay, nursing hours, and receiving physiotherapy during hospital stay.