OBJECTIVE: Evaluate safety and effects of training at moderate and high intensity intervals (MIIT, HIIT) compared to continuous moderate intensity training (MICT) in heart disease patient with very high cardiovascular risk (CVR). METHOD: Quasi-experimental study of 81 patients in a cardiac rehabilitation (CR) program, after risk stratification, all patients presented at least 2 factors with high CVR. All patients were provided supervised concurrent training: aerobic: initially 2 weeks MICT. subsequently MICT group with same prescription, MIIT 3 intervals of 3 'to 70-80% FCR with active pause exercise of 3' to 60 a 70% FCR, HIIT 3 intervals of 3'a 80-90% FCR with active pause exercise of 3 '70 a 80% FCR, resistance training 3 weekly sessions isotonic exercises and 1 calisthenics and multidisciplinary intervention. RESULTS: 81 patients assigned to: 61 MICT group, 13 MIIT and 7 HIIT, no significant differences were observed. Percentage gains were obtained in METs-load 45%, 60% and 86% (p = 0.17) and watts 51, 44 and 48 in MICT, MIIT, HIIT respectively (p = 0.54). Although there are no statistical significant intergroup differences if there is a greater improvement in MET-load in the HIIT group. There was no adverse outcome in any training. CONCLUSIONS: In very high cardiovascular risk heart disease patient, supervised interval training (MIIT/HIIT) is safe, with a tendency to greater improvement in exercise tolerance (METs-load) with HIIT compared to MICT.