In order to evaluate the significance of premature ventricular beats (PVBs) in childhood, 9 children (mean age 12.8 +/- 2.3 years) without clinical or in noninvasive investigational signs of heart disease, with occasional PVBs detected during early medical control, have been studied over periods ranging from 12 to 68 months. At the beginning and end of the follow-up period all children performed a step test, a maximal cycloergometric exercise test, 24-hour electrocardiographic monitoring, echocardiogram and routine laboratory examinations. While at first control complex PVBs were found in 4 children, at final control only 2 showed complex PVBs, 1 simple PVBs and 1 no PVB. Among the 5 children having simple PVBs at first control, only one showed complex PVBs at the end of the follow-up, with 3 simple PVBs and 1 no PVB. The disappearance of more dangerous PVBs (run of three or more) and also the large variability of arrhythmia (both for its presence and complexity) during the numerous tests, seem to demonstrate that in children with normal hearts the occurrence of PVBs can be considered as benign and free of adverse implications.