Introduction: Polycystic Ovary Syndrome (PCOS) is the most common endocrinopathy in young females, affecting 4-18% of the premenopausal population. PCOS is a metabolic disorder associated with increased cardiovascular disease risk. Exercise is an effective treatment strategy to manage symptoms and reduce cardiovascular disease risk factors in PCOS. High-intensity interval training (HIIT) has been suggested as a more efficient exercise modality in PCOS; however, the impact of HIIT compared to usual care moderate intensity steady state exercise (MISS) is hampered by small patient numbers and inconsistency in the methods employed.  Methods: We synthesized the available data through a systematic review and meta-analysis to compare the effectiveness of HIIT to MISS exercise without concurrent diet or pharmacological interventions. Our primary outcome measures assessed the impact of HIIT and MISS on cardiorespiratory fitness (CRF) and insulin resistance (IR), using measures of VO2max and HOMA-IR respectively. Secondary analyses compared the influence of exercise intensity on body composition and hormone and lipid profiles.  Results: A total of 17 studies ranging from 8 to 24 weeks in duration were included in the meta-analyses, with HOMA-IR assessed in 219 women (HIIT = 60; MISS = 159) and VO2max assessed in 222 (HIIT = 28; MISS = 194) women. MISS exercise significantly improved CRF (Δ = 1.081, p < 0.001), whereas HIIT resulted in no improvement (Δ = 0.641, p = 0.128). Both MISS (Δ = -0.341, p = 0.078) and HIIT (Δ = -0.257, p = 0.374) exercise showed no significant effect on IR. Fasting insulin was significantly reduced following MISS (p = 0.009) but not HIIT exercise. Body composition was significantly reduced by MISS exercise [BMI (p < 0.001); waist circumference (p < 0.001) and waist-to-hip ratio (p = 0.022)], whereas HIIT resulted in no significant differences. Neither HIIT nor MISS exercise had a significant impact on lipid profile..  Discussion: This is the first meta-analysis to investigate the impact of HIIT and MISS exercise intervention in PCOS. Surprisingly, our results contrast with previous literature in healthy and diseased cohorts following HIIT exercise, with a significant improvement in CRF only evident following MISS exercise and not HIIT. Additionally, there was a trend towards improvement in HOMA-IR following MISS exercise, which was not evident following HIIT. Therefore, in isolation, HIIT exercise may not provide superior outcomes in CRF and IR compared with MISS. The available data included in the meta-analysis was from low- and moderate-quality studies. There is therefore a lack of high-quality evidence to support these conclusions. High publication bias was also evident within the MISS exercise interventions, but was not present from HIIT intervention studies. Our analysis focused on isolated exercise interventions as opposed to combined interventions with pharmacological agents and/or diet which may explain some of the disparate outcomes in this analysis.  In conclusion, the small number of studies and participants, and low quality evidence highlight the need for larger randomised controlled trials to establish the true effect of isolated exercise interventions, especially HIIT, in the management of PCOS.