This study explores the nature of caring for elderly demented relatives living at home in Thailand. Structured and semi-structured interviews were carried out with 44 pairs of known cases of demented patients (subjects), who received treatment at out-patient departments (OPD) in three selected hospitals, and their principal carers. The Thai Mental State Examination (TMSE) and Behaviour Rating Scale (BRS) were applied to subjects, the Caregiver Strain Index (CSI) was applied to carers, and the Network Assessment tool was applied to both subjects and carers. Significant correlations were found between levels of strain in carers and the cognitive impairment and physical dependence of subjects. Spouse carers experienced significantly less strain, but reported more stress and physical strain and a poorer current relationship than younger relative carers. The vast majority of subjects (94%) and more than half (57%) of carers had a small support network. Three-quarters of carers needed information about dementia illness and how to provide care at home and two-thirds felt the elderly relative should receive financial support. Despite difficulties in caring, three-quarters of carers were still willing to continue to provide care. The primary motivation to care was derived from a strong filial obligation based on Buddhist belief of 'reciprocity.' The effects of the caring relationship and the quality of care need further investigation. Policy recommendations include providing health education, financial support, and carers support groups.