Objective: Omega-3 fatty acids, especially alpha-linolenic acid (ALA), which are present in nuts may reduce cardiovascular disease (CVD) risk, by changing vascular inflammation and improving endothelial dysfunction. The objective of the study was to evaluate the acute effects of two different diets, one containing walnuts and the other almonds on endothelial function. Methods: Twenty-seven overweight volunteers underwent a randomized 2-period, crossover, controlled intervention study. The subjects were given either walnut or almond diets which varied in monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA) content. The walnut diet provided 23.1% energy from PUFA and the almond diet provided 7.6% energy from PUFA. Endothelial function was assessed physiologically by flow-mediated dilation (FMD) and biochemically by sVCAM (soluble vascular cell adhesion molecules). Results: The walnut diet significantly improved FMD (p = 0.004) and decreased sVCAM (p = 0.009) whereas the almond diet tended to improve FMD (p = 0.06) and significantly decreased sVCAM (p = 0.004). Conclusion: Both walnut and almond diets improved FMD and sVCAM and there was no significant difference in physiological and biochemical markers between the two diets.