Fifteen patients (5 men, 10 women, mean age 64.3 ± 1.8 years) with mild chronic heart failure (NYHA functional class II to III, ejection fraction 30–40%) were randomly assigned to 6 weeks of intensive home-based hydrotherapy or 6 weeks of restriction in a crossover intervention trial. Quality of life and heart-failure-related symptoms were assessed by means of a validated questionnaire. A graded bicycle exercise test with incremental workloads (0, 50, 75 and 100 W) was performed at the end of each treatment period. The hydrotherapeutic programme consisted of a structured combination of daily home-based external warm- and cold-water applications. Baseline characteristics were balanced between the groups. With hydrotherapy, a significant improvement in three of six dimensions of quality of life (mood, physical capacity and enjoyment) and a significant reduction in heart-failure-related symptoms was found. Heart rates at rest and at 50-W workload were significantly reduced by hydrotherapy; blood pressure decreased non-significantly at rest and during exercise. The hydrotherapeutic treatment was well accepted and no relevant adverse effects were observed. The authors concluded that a home-based hydrotherapeutic thermal treatment programme improves quality of life, heart-failure-related symptoms and heart rate response to exercise in patients with mild chronic heart failure.