Nine children who had undergone total correction of tetralogy of Fallot were studied with the purpose of observing the physical changes that might be produced by a period of rehabilitation in hospital and comparing these results with those of a control group having the same pathology but which had not followed a protocol for physical activity. Precise criteria were used in the selection of the patients. Careful clinical examinations and exercise tests were conducted before and after the programme, in particular maximal stress testing on the bicycle ergometer and submaximal exercise on the treadmill. The sessions were held three times weekly in a gymnasium over three months, gradually increasing the duration of each session to a maximum of one hour. During the session, heart rate was monitored with a Sport-tester 3000 so as not to exceed 60%, then 70%, of the maximal heart rate recorded during the stress test. Testing at the end of the programme demonstrated an improvement in tolerance under maximal stress in 7 of the 9 patients. As for submaximal performance, 8 out of 9 children covered a greater distance using the same parameters as for initial testing. At the end of the programme, the children all showed increased independence and initiative and more self-confidence in establishing social relations. The programme has proven to be a comprehensive method for safely improving physical fitness in these patients and represents an important starting point for a better future.