This study explored burden and social networks in families of patients with schizophrenia or a long-term physical disease. It was carried out in 169 specialised units (mental health department, and units for the treatment of chronic heart, brain, diabetes, kidney, lung diseases) recruited in 30 randomly selected geographic areas of Italy. The study sample consisted of 709 key relatives of patients with a DSM-IV diagnosis of schizophrenia and 646 key relatives of patients with physical diseases. Each relative was asked to fill in the Family Problems Questionnaire (FPQ) and the Social Network Questionnaire (SNQ). In all selected pathologies, the consequences of caregiving most frequently reported as always present in the past 2 months were constraints in social activities, negative effects on family life, and a feeling of loss. Objective burden was higher in brain diseases, and subjective burden was higher in schizophrenia and brain diseases than in the other groups. Social support and help in emergencies concerning the patient were dramatically lower among relatives of patients with schizophrenia than among those of patients with physical diseases. In the schizophrenia group, both objective and subjective burden were significantly higher among relatives who reported lower support from their social network and professionals. The results of this study highlight the need to provide the families of those with long-term diseases with supportive interventions, including: (a) the management of relatives' psychological reactions to patient's illness; (b) the provision of information on the nature, course and outcome of patient's disease; (c) training for the relatives in the management of the patient's symptoms; and (d) the reinforcement of relatives' social networks, especially in the case of schizophrenia.