The aim of this study was to determine the current practices of established general practitioners in managing patients with drug and alcohol-related problems and identify gaps in training. A random sample of general practitioners completed a survey assessing diagnostic skills and referral practices concerning alcohol and illicit drug use in general practices in February 1999, comprising 110 general practitioners registered with the Central Sydney Division of General Practice. The main outcome measures were competent skills and knowledge, willingness to treat. The majority (96%) of GPs provided clinically appropriate responses for at least one drug category, although none received this rating for all six. Most general practitioners reported that they were unwilling to treat heroin and cocaine problems themselves but expressed willingness to refer patients appropriately. More than a quarter of general practitioners were unaware of the safe drinking levels for men and women or the appropriate treatment for patients consuming above such levels. Age, years in practice, type of practice, willingness to obtain drug use histories and post-graduate training were all significantly associated with general practitioners' willingness to treat and competence in managing drug and alcohol-related problems. In this study, general practioners reported low levels of skills and referrals for treatment of illicit drug use and suboptimal skills in the management of alcohol problems. The results suggest that a more comprehensive approach to education and training is required to bring about a change in practice behaviour. [Fucito LM, Gomes BS, Murnion B, Haber PS. General practitioners' diagnostic skills and referral practices in managing patients with drug and alcohol-related health problems: implications for medical training and education programmes.