Obesity and overweight have great clinical and social significance and are associated with a number of medical and surgical complications. We attempt here to summarize current knowledge on the subject and describe the research we are presently carrying out in this field. After a brief introduction, definition, and discussion of etiopathogenesis, the indexes of ponderal excess and epidemiology are illustrated. The cardiovascular adjustments and the relationships between obesity and hypertension, ischemic heart disease and congestive heart failure are then treated. One aim of our investigation was to study the modifications of an entire set of biological and clinical parameters which could concretely formulate and/or identify some pathophysiological links between obesity and heart disease. We thus studied obese subjects with hypertension, diabetes and multiple cardiovascular risk factors. We also studied a group of asymptomatic obese subjects, whom we define as "the healthy obese". Our results, supported by the medical literature, led to the conclusion that obesity is an important and/or independent cardiovascular risk factor. We think, however, that it would be prudent to await for the results of interventional trials and follow-up studies involving a large number of young, healthy obese subjects in order to monitor the most important biological variables over the long term.