Fibrinogen is an important risk factor for atherosclerosis, stroke and cardiovascular heart disease (CHD). This risk is increased when associated with a high serum cholesterol. Furthermore, it is also believed that not only fibrinogen concentration, but also the quality of fibrin networks may be an important risk factor for the development of CHD. CHD and stroke as a result of atherosclerosis, plus the related problems of hyperinsulinaemia, hyperlipidaemia and hypertension are strongly related to diet. The "western" diet, defined by low fibre and high fat, sucrose and animal protein intakes, appears to be a major factor leading to death. It has been established that the water-soluble dietary fibre, pectin, significantly decrease the concentration of serum cholesterol levels. Evidence is also accumulating that a diet rich in fibre may protect against diseases associated with raised clotting factors. This investigation studied the possible effects of pectin on fibrinogen levels and fibrin network architecture. Two groups of 10 male hyperlipidaemic volunteers each, received a pectin supplement (15 g/day) or placebo (15 g/day) for 4 weeks. Lipid and fibrin network structure variables were measured at baseline and the end of supplementation. Pectin supplementation caused significant decreases in total cholesterol, low-density lipoprotein cholesterol, apolipoprotein A & B and lipoprotein (a). Significant changes in the characteristics of fibrin networks developed in the plasma of the pectin supplemented group indicated that networks were more permeable and had lower tensile strength. These network structures are believed to be less atherogenic. It is suspected that pectin modified network characteristics by a combination of its effects on metabolism and altered fibrin conversion. This confirms the therapeutic possibilities of dietary intervention. Furthermore, this study also showed that changes in plasma fibrinogen need not be present to induce alterations in fibrin network architecture.