Objective: Both gender and meal fatty acid composition modulate postprandial triacylglycerol (TAG) metabolism, but little information exists on their interaction. We compared postprandial TAG concentrations in men and women after test meals differing in the proportion of monounsaturated (MUFA) and saturated fatty acids (SFA). Subjects: Nine men (body mass index, BMI: 24.572.3 kg/m 2 ) (mean7s.d.) and 10 premenopausal women (BMI: 21.271.7 kg/m 2 ), young and healthy, habituated to a relatively high MUFA diet. Design: Plasma responses were studied after subjects consumed two meals, each providing 60 g of fat and 4.7 MJ, on different occasions: one meal was rich in MUFA (MUFA meal: 40 g MUFA; 12 g SFA) and the other meal was rich in SFA (SFA meal: 20 g MUFA; 32 g SFA). The total body and abdominal fat mass were assessed by dual energy X-ray absorptiometry. Results: Fasting plasma TAG concentration did not differ between meals or genders. No gender differences were observed in either total body or abdominal fat mass. The area under the plasma concentration vs time curve was on average 60% higher (Po0.001) in men than women. Repeated measures ANOVA showed a significant effect of meal  time interaction in men (Po0.001) but not in women (P ¼ 0.84). In men, maximal plasma TAG occurred at 4 h and was significantly greater after the MUFA meal (2.1070.20 mmol/l) (mean7s.e.m.) than after the SFA meal (1.6670.19 mmol/l) (P ¼ 0.01). TAG concentration at 5 h was also significantly greater after the MUFA meal. In women, the patterns of TAG responses were identical after the MUFA and SFA meals. Conclusions: This study provides evidence that gender influences postprandial TAG concentrations when meal fatty acid composition is altered.