Background: Changes in the demographics and respective growth of life expectancy and social needs make informal caregiving crucial component of comprehensive health and social care network, which substantially contributes to the health and well-being of the elderly. The purpose of this paper is to understand the system of care of elderly patients with mental disorders from the perspective of informal caregivers in Lithuania. Methods: We conducted five semi-structured focus group discussions with 31 informal caregivers attending to elderly patients with mental disorders. The data were audiotaped and transcribed verbatim. A thematic analysis was subsequently performed. Results: Five thematic categories were established: (1) the current state of care-receivers: Representation of the complexity of patients' physical and mental condition. (2) The current state of caregivers: Lack of formal caregivers' integration as a team; inadequate formal involvement of informal caregivers. (3) Basic care needs: The reflection of the group needs relating directly to the patient, care organisation and the caretaker. (4) The (non-) Readiness of the existing system to respond to the needs for care: Long-term care reliance on institutional services, lack of distinction between acute/immediate care and nursing, lack of integration between the medical sector and the social care sector. (5) Potential trends for further improvement of long-term care for the elderly with mental disorders. Conclusions: Strengthening of the care network for elderly patients with mental disorders should cover more than a personalised and comprehensive assessment of the needs of patients and their caregivers. Comprehensive approaches, such as formalization of informal caregivers' role in the patient care management and planning, a more extensive range of available services and programs supported by diverse sources of funding, systemic developments and better integration of health and social care systems are essential for making the system of care more balanced.