The effect of taurine on the development of atherosclerotic lesions in rabbits maintained on a 2% cholesterol diet for a 14 week period has been examined. Taurine (0.2 and 0.5%) administered in the drinking water reduced thoracic aorta involvement. The area covered by atherosclerotic lesions was 58 +/- 15 and 52.5 +/- 12% (P less than 0.05) respectively, compared to 72.4 +/- 19% in the control group. Taurine had no significant effect on serum or tissue cholesterol, calcium, triglyceride or phospholipid concentrations. Nevertheless 0.2% taurine caused an increase in dP/dtmax (measured from the systemic blood pressure) and 0.5% lowered systemic blood pressure. The anti-atherosclerotic effects of taurine appear to be unrelated to a fall in blood pressure. The possibility that taurine is reducing the development of atherosclerotic lesions through a mechanism involving its antioxidant activity is discussed.