ABSTRACT: INTRODUCTION: To study exercise capacity and heart rate (HR) recovery after peak exercise in morbidly obese female patients with obstructive sleep apnoea (OSA). METHODS: Twenty-four morbidly obese female patients (36.17 ± 9.20 years and 45.20 ± 5.41 kg.m-2) newly diagnosed with OSA underwent cardiopulmonary exercise testing (CPET) for assessment of peak oxygen uptake (V’O2) and heart rate (HR) recovery at 30, 60 and 90 seconds. Comparisons were made between mild (apnoea-hypopnea index [AHI] <15 h-1) and moderate-to-severe (AHI ≥15 h-1) OSA. RESULTS: For the entire study population, peak V’O2 was 15.58 ± 2.44 ml.min-1.kg-1. No differences in peak V’O2 were found between moderate-to-severe and mild OSA (16.11 ± 2.37 vs. 15.19 ± 2.50 ml.min-1.kg-1, p=.371, respectively). HR recovery registered at any time after the peak workload also did not differ between both groups. Nonetheless, the percentage of HR decrease at 90 seconds of recovery time was almost statistically significantly lower in the patients with moderate-to-severe OSA (p=.073), and it was negatively correlated with the oxygen desaturation index (r =-0.679, p=.044). CONCLUSION: Exercise capacity is not different between patients with mild and moderate-to-severe OSA. Nevertheless, patients with moderate-to-severe OSA tend to have a slower HR recovery response to exercise than those with milder OSA. Finally, the oxygen desaturation index is related to this slower chronotropic response.