OBJECTIVE To examine the impact of a web-based personalized feedback intervention, the Check Your Drinking (CYD; www.CheckYourDrinking.net) screener at 12-month follow-up. METHODS Respondents (N = 185) were recruited from a general population telephone survey of Ontario, Canadian adults (> or =18 years) by asking risky drinkers if they were willing to help develop and evaluate Internet-based interventions for drinkers. Those randomly assigned to the intervention condition were provided with the web address and a unique password to a study-specific copy of the CYD. Respondents assigned to the control condition were sent a written description of the different components of the CYD and asked how useful they thought each of the components might be. Respondents were followed up at 3, 6 and 12 months. RESULTS By the 12-month follow-up, the impact of the intervention previously reported at 3 and 6 months of CYD on problem drinkers' alcohol consumption was no longer apparent (P > 0.05). CONCLUSIONS Recognizing that many people with alcohol concerns will never seek treatment, recent years have seen an increase in efforts to find ways to take treatment to problem drinkers. The CYD is one such intervention that has a demonstrated effect on reducing alcohol consumption in the short term (i.e. 6 months). Other more intensive Internet-based interventions or interventions via other modalities may enhance this positive outcome over the short and long term among problem drinkers who would be otherwise unlikely to access treatment for their alcohol concerns.