Introduction: MicroRNA’s (miRNAs) are single stranded RNAs, which negatively regulate gene expression by repressing mRNA translation (Churov, Oleinik and Knip, 2015). They are essential intracellular mediators of inflammation in exercise adaptation (Davidson-Moncada, Papavasiliou and Tam, 2010) and their expression is inherent in the inflammatory post-acute exercise response. However, the effects of exercise stimuli of variable type and intensity on circulating miRNA expression has not yet been established. Consequently, this study will assess the impact of acute aerobic and resistance exercise on miRNAs associated with inflammation (miRNA-146a, miRNA-155 and miRNA-222). Methods: Following institutional ethical approval, 10 healthy recreationally active males (Age=24±3 years; BMI =25.5±2.8kg/m2, mean±sd) volunteered for the study. They were assessed for maximal aerobic capacity (VO2max) and maximal strength at leg press (6-10 repetition maximum (RM) sub-maximal protocol). Thereafter they completed 1 aerobic exercise trial: 30 minutes of sub-maximal cycling at a workload equivalent to 70% VO2max, plus 2 lower body resistance exercise trials: 3 sets of repetitions to failure at 30%1RM and 3 sets of 10 repetitions at 70%1RM. Exercise trials were randomised and separated by a washout period of 3-7 days. Venous blood samples were collected pre- and immediately post- exercise. Real-time quantitative polymerase chain reaction (RT-qPCR) analyses were performed to investigate acute changes in circulating miRNAs associated with inflammation, log2fold expression was then calculated from the RT-qPCR data. Results: Following aerobic and 30%1RM resistance exercise, miRNA-146a increased (1.52±3.64 and 0.07±0.56 respectively) whilst levels decreased post 70%1RM resistance exercise (-0.46±0.69). Both MiRNA-155 and miRNA-222 levels increased in all trials (aerobic=0.55±0.46, 30%1RM=0.41±0.75, 70%1RM=0.52±0.85; aerobic=1.41±3.84, 30%1RM=0.41±0.62, 70%1RM=0.05±0.44 respectively). One way repeated measures ANOVA revealed no significant differences between the trials (miRNA-146a=F(1.07, 9.65)=2.289, p=0.162; n2=0.203; miRNA-155=F(2, 18)=0.111, p=0.896; n2=0.012; miRNA-222= F(1.07, 9.62)=0.981, p=0.353; n2=0.098), whilst a large effect size was only identified between 30%1RM and 70%1RM in miRNA-146a (d=0.85). Conclusion: Our findings suggest that acute aerobic and resistance exercise induces small changes in miRNA expression. Both aerobic and 30%1RM resistance exercise resulted in increased miRNA expression; however, the magnitude of change was minimal. The major limitation in this study was the small sample size, which may have impacted our findings. Nevertheless, the impact of changes in miRNA expression is not known and longitudinal studies are required to examine the role of miRNA in mediating inflammation in response to varying exercise modes and intensities.