Summary•An experimental group of community psychiatric nurses (CPNs) were trained to undertake psychosocial intervention with families caring for a sufferer from schizophrenia. Intervention consisted of a detailed assessment of all the needs of each family member, health education and family stress‐management programmes. Outcome was compared with a control group of families who received standard CPN care.•This report concerns the evaluation of one component of the intervention, namely, health education. A key relative's functional knowledge about schizophrenia was assessed at pre‐test, post‐test and 6‐month follow‐up using the Knowledge about Schizophrenia Inventory (KASI). The KASI is a tape‐recorded and semi‐structured interview schedule which is scored by reliable raters and which yields a global knowledge score from six subscales. Both the control and experimental CPNs were trained to administer the KASI.•Analysis revealed that the KASI scores of the control group of relatives did not significantly change over the 12‐month period of the study. However, global KASI scores in the experimental group improved significantly both post‐test and at 6‐month follow‐up. These results are discussed in relation to the ‘stress‐vulnerability’ model of schizophrenia and the implications for CPNs (and other community based mental health professionals) are considered. It is argued that there are both sound theoretical and practical reasons for providing families with information about schizophrenia which should be addressed by appropriat