Background High prevalence diseases, such as high blood pressure, dementia and depression in old age can lead to multimorbidity, which is often defined as the presence of more than one health condition in an individual. Multimorbidity has negative consequences on health-related quality of life and healthcare utilization. As many age-associated diseases are not curable, therapeutic goals like preservation of autonomy, functioning, and life satisfaction become more important in old age patients. Objective The prevalence of multimorbidity dementia and depressive symptoms and the consequences of multimorbidity on autonomy, functioning, and life satisfaction among the oldest old were examined. Material and methods In personal computer-assisted interviews, participants of the representative study NRW80+ were asked for which health issues they received medical treatment. Results On average, people above the age of 80 years were treated for 3.62 diseases and 31.4% of older people received medical treatment for 5 or more diseases. A connection between multimorbidity and age group could not be shown. Autonomy, functioning, and life satisfaction are reduced in association with multimorbidity. Conclusion Multimorbidity is a frequent phenomenon among old people. A lack of diagnostic procedures and medical treatment can be a reason for the missing age trends. The results illustrate the importance of multimorbidity for patient-relevant outcomes and reveal the need to identify patients with multimorbidity.