The prevention of arterial thrombotic disease has a high priority in developed countries. We have focused our studies on the antithrombotic activity of those fruits and vegetables with the potential to prevent the disease, and the present study was undertaken as part of a series of investigations to examine beneficial fruits and vegetables. For this purpose, suitable laboratory tests as well as diets have been devised. In the current investigation, we have classified various tomato varieties with antithrombotic properties, and we now have extended our overall data to include more than ten antithrombotic varieties of fruits and vegetables. A method designed to measure shear-induced platelet activity (the Global Thrombosis Test, GTT) was used to assess haemostasis in vitro and a He-Ne laser-induced thrombosis technique was utilized to examine arterial thrombogenesis in vivo. Concentrations of the antioxidant, lycopene, were also measured. Three mini-type tomato varieties, coded “Cin”, “Pik” and “Caec”, and one mediumtype variety, coded “K”, were harvested at different stages of maturity. All mini-type varieties demonstrated antithrombotic activity at an early (green) stage. The antithrombotic activity decreased with the maturation of “Cin” and “Caec” but remained constant at all stages of maturity with “Pik”. The medium variety, “K”, did not possess antithrombotic activity. Lycopene was not detected at any stage in any of the tomato varieties, suggesting that this antioxidant did not contribute to antithrombotic activity. The present results indicated that the antithrombotic activity of tomatoes is dependent on the particular variety and stage of maturity, and that this activity is not due to lycopene.