Obesity is an important public health issue with an epidemic spread in adolescents and children, which needs to be tackled. This systematic review of primary care physicians' knowledge, attitudes, beliefs and practices (KABP) regarding childhood obesity will help to implement or adjust the actions necessary to counteract obesity. Eligible studies were identified through a systematic database search for all available years to 2007. Articles were selected if they included data on primary care physicians' KABP regarding childhood obesity: 130 articles were assessed and eventually 11 articles covering the period 1987–2007 and responding to the inclusion criteria were analyzed. The included studies showed that almost all physicians agreed on the necessity to treat childhood obesity but they believed to have a low self-efficacy in the treatment and experienced a negative feeling regarding obesity management. There was a large heterogeneity in the assessment of childhood obesity between the different studies but the awareness of the importance of using body mass index increased over the years among physicians. Almost all studies noted that physicians recommended dietary advice, exercise or referral to a dietician. From this review, it is obvious that there is a need for education of primary care physicians to increase the uniformity of the assessment and to improve physicians' self-efficacy in managing childhood obesity. Multidisciplinary treatment including general practitioners, paediatricians and specialized dieticians appears to be the way to counteract the growing obesity epidemic and thus, primary care physicians have to initiate, coordinate and obviously participate in obesity prevention initiatives.