Objectives: Uremic toxins such as indoxyl sulfate (IS), p-cresyl sulfate (pCS), and indole-3-acetic acid (IAA) produced by the gut microbiota are recognized as risk factors for many comorbidities, including cardiovascular diseases. Patients with chronic kidney disease (CKD) have an accumulation of these toxins, and nutritional strategies have been proposed to mitigate gut dysbiosis and, consequently, reduce these toxins. This study aimed to evaluate the effects of resveratrol supplementation on the plasma levels of IS, pCS, and IAA in nondialyzed patients with CKD. Methods: In this placebo-controlled crossover study, twenty nondialyzed patients were randomly divided into two groups: they received either one capsule/day containing 500 mg of trans-resveratrol (63 ± 7.5 years, glomerular filtration rate [GFR]: 34 ± 14 mL/min, body mass index: 26.8 ± 5.6 kg/m2) or a placebo containing 500 mg wheat flour (62 ± 8.4 years, GFR: 34 ± 13 mL/min, body mass index: 28.6 ± 4.4 kg/m2) during 4 weeks. After 8 weeks of washout (no supplementation), another 4 weeks of supplementation with crossover was initiated. IS, IAA, and pCS plasma levels were quantified by the reverse phase high-efficiency liquid chromatography method with fluorescent detection. The mRNA expression of nuclear factor erythroid 2-related factor 2 and nuclear factor kappa B in peripheral blood mononuclear cells was evaluated by polymerase chain reaction. C-reactive protein plasma levels were also evaluated. Results: As expected, the uremic toxin levels were negatively correlated with the GFR, but no effect of trans-resveratrol supplementation was found on levels of IS, IAA, and pCS. There was a positive correlation between IS and nuclear factor erythroid 2-related factor 2 (r = 0.24, P = .03) and also between IS and C-reactive protein (r = 0.21, P = .05). Conclusion: Supplementation with trans-resveratrol did not reduce the plasma levels of IS, pCS, and IAA in nondialyzed patients with CKD. The interactions among uremic toxins and anti-inflammatory and proinflammatory pathways deserve more studies.