Hypochlorite seems to inhibit platelet aggregation in the platelet-rich plasma (PRP) by modifying fibrinogen receptors. The hypochlorite-inactivated isolated platelets are completely repaired by native plasma. Platelet aggregation in PRP is suppressed by hypochlorite by its direct interaction with cells and indirectly due to plasma modification. The indirect action of hypochlorite is a reversible reaction between the platelet active groups and the products of plasma modification. The reaction may involve sulphur-containing groups. The spin-probe method shows that hypochlorite penetrates into the lipid phase of human blood lipoproteins. It initiates lipid peroxidation and causes the disturbance of the lipid structure and the protein please.