Objectives: In patients with heart failure (HF), peak oxygen consumption (peak VO<sub>2</sub>), the relationship between minute ventilation and carbon dioxide production (VE/VCO<sub>2</sub> slope) and heart rate recovery (HRR) are established prognostic predictors. However, treadmill exercise has been shown to elicit higher peak VO<sub>2</sub> values than bicycle exercise. We sought to assess whether the VE/VCO<sub>2</sub> slope and HRR in HF also depend on the exercise mode. Methods: Twenty-one patients with mild HF on chronic β-blocker therapy underwent treadmill and bicycle cardiopulmonary exercise testing for measurement of peak VO<sub>2</sub> and the VE/VCO<sub>2</sub> slope. In patients with sinus rhythm (n = 16), HRR at 1 (HRR-1) and 2 min (HRR-2) after exercise termination was assessed. Results: Peak VO<sub>2</sub> was higher during treadmill as compared with bicycle testing (21.7 ± 4.6 vs. 19.6 ± 3.4 ml/kg/min; p = 0.006). HRR-1 tended to be slower (15 bpm, interquartile range 8–19, vs. 18 bpm, interquartile range 11–22; p = 0.16), and HRR-2 was significantly slower after treadmill exercise (26 bpm, interquartile range 20–39, vs. 31 bpm, interquartile range 22–41; p = 0.04). In contrast, VE/VCO<sub>2</sub> slope values did not differ between the test modes (32.9 ± 5.5 vs. 32.3 ± 5.0; p = 0.56). Conclusions: In contrast to peak VO<sub>2</sub> and HRR, the VE/VCO<sub>2</sub> slope is not affected by the exercise mode in patients with mild HF.