Aims Recent increases in heart failure tend to overload the healthcare system. Consequently, there is a need for innovative strategies to reduce heart failure hospitalizations. Methods and results A multicentre randomized controlled trial was carried out to test the hypothesis that telemonitoring reduces heart failure hospitalizations during 1 year follow-up. The mean age of the 382 participating patients was 71.5 (32–93) years; the mean left ventricular ejection fraction was 0.38, and in 61% it was ≤0.45%. Mean time to first heart failure-related hospitalization was 161 days for the intervention group and 139 days for the usual-care group; hospitalizations occurred in 18 (9.1%) compared with 25 (13.5%) patients, with a total number of 24 and 43 hospitalizations, respectively [Kaplan–Meier P = 0.151, hazard ratio (HR) 0.65, 95% confidence interval (CI) 0.35–1.17]. Subgroup analysis of the primary endpoint showed benefits for three subgroups: duration of heart failure, having a pacemaker, and co-habiting. The combined endpoint of heart failure admission and all-cause mortality was similar for both groups (Kaplan–Meier P = 0.641, HR 0.89, 95% CI 0.69–1.83). No differences were found regarding secondary endpoints, except for the reduced number of face to face contacts with the heart failure nurse (Mann–Whitney P < 0.001). Mortality was 18 (9.1%) in the intervention group and 12 (6.5%) in the usual-care group (Mann–Whitney P = 0.34, Cox regression analysis P = 0.82). Conclusion No significant differences were found regarding the primary endpoint, possibly caused by a relative underpowering of the population combined with well-treated study groups. However, telemonitoring tends to reduce heart failure (re)admissions and significantly decreases contacts with specialized nurses. Further research with pre-specified groups, as found in the subgroup analysis, is needed.