Joint hypermobility syndrome (JHS) and Ehlers-Danlos syndrome, hypermobility type (EDS-HT) are two clinically overlapping heritable connective tissue disorders strongly associating with pain, fatigue and other secondary aspects. Though not considered a diagnostic criterion for most EDS subtypes, cardiovascular involvement is a well-known complication in EDS. A case-control study was carried out on 28 adults with JHS/EDS-HT diagnosed according to current criteria, compared to 29 healthy subjects evaluating resting electrocardiographic (ECG), 24-h ECG and resting heart ultrasound data. Results obtained in the ECG studies showed a moderate excess in duration of the PR interval and P wave, an excess of heart conduction and rate abnormalities and an increased rate of mitral and tricuspid valve insufficiency often complicating with "true" mitral valve prolapse in the ecocardiographic study. These variable ECG subclinical anomalies reported in our sample may represent the resting surrogate of such a subnormal cardiovascular response to postural changes that are known to be present in patients with JHS/EDS-HT. Our findings indicate the usefulness of a full cardiologic evaluation of adults with JHS/EDS-HT for the correct management.