Seventy-three healthy participants (control group; n=45) and treatment-resistant depression patients (patient group; n=28) were randomized to receive a single oral liquid dose of 1mL/kg of ayahuasca or placebo in this randomized, double-blinded, placebo-controlled trial investigating the effects of ayahuasca on blood inflammatory biomarkers, as well as the correlation of these biomarkers with depressive symptoms. The primary outcome of interest was depression severity as measured by the Montgomery-Åsberg Depression Rating Scale (MADRS). Other outcome measures include the quantification of plasma C-reactive protein (CRP) and serum interleukin 6 (IL-6), cortisol, brain-derived neurotrophic factor (BDNF), glutamic oxalacetic transaminase (GOT), and glutamic pyruvic transaminase (GPT) inflammatory biomarker levels which were quantified from blood samples. At baseline, patients showed higher CRP levels than healthy controls and a significant negative correlation was found between these elevated levels of CRP and serum cortisol. At 2 days post-treatment, patients treated with ayahuasca showed a significant reduction of CRP levels, which was also found to be significantly correlated with lower depressive symptoms. No other significant results were found for other biomarkers.