© 2020 Elsevier Ltd Background: Evidence supports positive effects of acute exercise on mood states. Non-traditional exercise modalities, including Pilates, remain understudied, particularly among males. This study examined mood state responses to a single Pilates bout among young adult males, and explored if responses differed according to analogue Generalized Anxiety Disorder (AGAD) or depression status, or physical activity level. Methods: Eighty-seven young adult males completed 30-min of mat-based Pilates. Outcomes included state anxiety, worry, feelings of tension, depressed mood, anger, energy and fatigue, and total mood disturbance (TMD). Paired samples t-tests compared pre- and post-session means within the group; magnitude of change was quantified with standardized mean differences. Two condition X two time repeated measures ANOVA examined outcome differences according to AGAD and depression status, and physical activity level. Results: Acute Pilates significantly reduced state anxiety, feelings of fatigue, and TMD, and significantly increased feelings of energy (allp ¿ 0.007). Small-to-moderate effect sizes were found for state anxiety, feelings of energy and fatigue, and TMD (all d = 0.22-0.51). Pilates resulted in significant improvements in state anxiety, feelings of fatigue and energy, and TMD among participants with AGAD (n = 28) (all d = 0.10-0.32, p < 0.007) and depressed (n=41) participants (all d = 0.01-0.19, p < 0.008). Conclusions: Notwithstanding potential limitations, including the absence of a control group and a lack of follow-up beyond immediate effects, this is the first report to support potential positive mood state responses to an acute bout of Pilates among young adult males. Findings varied based on analogue GAD and depression statuses, and physical activity level.