Walnut consumption produces beneficial cardiovascular effects. The aim of the present study is to compare the effects of meat enriched in walnut paste (WM) and low-fat meat (LM) consumptions on platelet aggregation, plasma thromboxane A₂(TXA₂, measured as TXB₂), prostacyclin I₂(PGI₂, as 6-keto-PGF_1α) and the thrombogenic ratio (TXB₂/6-keto-PGF_1α) in volunteers at high CVD risk. Twenty-two adults were placed on a random, non-blinded crossover study involving two test periods (five portions WM/week for 5 week; five portions LM/week for 5 week) separated by a 4- to 6-week washout period. The participants were asked to complete a diet record throughout the study. Platelet aggregation, plasma TXB₂, 6-keto-PGF_1αproduction and the TXB₂/6-keto-PGF₁α ratio were determined at baseline and at weeks 3 and 5 for the two dietary periods. The WM diet contains a lower SFA content, a higher concentration of PUFA and a more favourablen-6/n-3 ratio than the LM diet. Significant time × treatment interactions were observed for TXB₂(P = 0·048) and the TXB₂/6-keto-PGF₁α ratio (P = 0·028). The WM diet significantly increased the level of 6-keto-PGF₁α (P = 0·037) and decreased the TXB₂/6-keto-PGF₁α ratio (P = 0·048). At week 5, significant differences (P < 0·05) between treatments were found for maximum aggregation rate, TXB₂values and the TXB₂/6-keto-PGF₁α ratio. The effects on TXB₂and the TXB₂/6-keto-PGF₁α ratio were time-course dependent (P = 0·019 and 0·011, respectively). The WM and LM diets reduced TXB₂levels most (P = 0·050) in obese individuals, while the TXB₂/6-keto-PGF₁α ratio decreased most (P = 0·066) in volunteers whose serum cholesterol levels were ≥ 2200 mg/l. The WM diet should be considered a functional meat because it improves the thrombogenic status mainly in individuals with high-cholesterol levels or high BMI.