To evaluate the effect of bezafibrate on the haemorheological pattern, 30 atherosclerotic non-diabetic patients were enlisted in a double-blind, comparative, parallel group trial with bezafibrate (600 mg daily) or placebo being randomly assigned. The 45-day treatment period was preceded by a three week pharmacological wash-out. Haemorheological parameters such as whole-blood, plasma and serum viscosity, haematocrit, fibrinogen, fibrinogen/albumin ratio and erythrocyte filterability were evaluated before and at the end of treatment. The results showed no change in haemorheological determinants in the placebo-treated group but a significant reduction in whole-blood viscosity, in haematocrit, in fibrinogen and fibrinogen/albumin ratio was observed in the bezafibrate treated patients. No variation was present in the plasma and serum viscosity and in the erythrocyte filterability.