Cardiovascular disease is a serious cause of mortality in the United Kingdom. Hyperlipidaemia is considered to be a major modifiable risk factor for the development of this disease. Large UK trials undertaken in primary care have shown relatively small reductions in risk factors for CVD including lipid levels and have led some to question whether diet is an effective treatment for hyperlipidaemia. However, many intervention trials failed to take account of the complexity of behaviour change as outlined by theoretical models of behaviour change. This study applied motivational interviewing to dietary education for people with hyperlipidaemia. 121 hyperlipidaemic patients who had been referred to a hospital dietetic department for dietary advice were randomised to receive either standard or motivational dietary interventions for a period of three months. Outcomes assessed included dietary knowledge, stage of dietary change, dietary intakes, lipid levels, and body mass indices. Both methods of dietary intervention resulted in improvements in dietary habits and knowledge, significant reductions in dietary fat and energy intakes, a significant reduction in body mass indices, and also progression in stage of change. However, reduction in serum cholesterol was statistically non-significant. The effectiveness and future role of dietary intervention in the treatment of hyperlipidaemia is, consequently, uncertain. There were no statistically significant differences in outcomes between the intervention groups. Therefore, motivational interviewing was not more effective than standard dietary advice in dietary education for people with hyperlipidaemia.