BACKGROUND: Due to illness-related functional limitations, a significant proportion of individuals with severe mental illness are dependent on external assistance to navigate their daily lives and achieve an optimal level of independence and wellbeing. OBJECTIVES: The present study sought to investigate the needs, the coverage of needs and the influencing factors among people with severe mental illness in Germany. METHODS: The study included patients diagnosed with severe mental illness. The met and unmet needs, as well as the potential influencing factors, were collected using Camberwell Assessment of Need (CAN) and Client Sociodemographic and Service Receipt Inventory (CSSRI) and subsequently analysed descriptively and exploratively. RESULTS: The mean number of reported needs was 6.4, with an average of 40.6% of these needs being met. The vast majority of patients (98%) require professional support, which is, from their perspective, inadequate (9-86% depending on the area concerned). Additionally, many patients also receive support from relatives (7-57% depending on the area concerned). The diagnosis, age, functioning, household income, and housing situation have an influence on the number and coverage of needs. CONCLUSIONS: The findings indicate that patients have diverse and complex needs, which are not fully met. Notably, the support provided by professional services is perceived as inadequate.