OBJECTIVE This paper reports an evaluation of the effectiveness and cost-effectiveness of nurse-led screening and brief intervention in reducing excessive alcohol consumption among patients in primary health care. BACKGROUND Excessive alcohol consumption is a major source of social, economic and health problems. However, such consumption is responsive to brief alcohol intervention. To date, brief intervention research in primary health care has focused on general practitioner-led interventions, and there is only circumstantial evidence of effectiveness in nurse-led interventions. However, nurses are increasingly taking a lead in health promotion work in primary care. METHODS A pragmatic cluster-randomized controlled trial was carried out between August 2000 and June 2003 to evaluate the effects of a brief intervention compared with standard advice (control condition). A total of 40 general practice clusters (intervention = 21 and control = 19) recruited 127 patients (intervention = 67 and control = 60) to the trial. Excessive consumption was identified opportunistically via the Alcohol Use Disorders Identification Test. After baseline assessment, patients received either a 5-10 minutes brief intervention using the 'Drink-Less' protocol or standard advice (control condition). Follow-up occurred at 6 and 12 months postintervention. RESULTS Analysis of variance weighted for cluster size revealed no statistically significant differences between intervention and control patients at follow up. A majority of patients in both conditions reduced their alcohol consumption between assessment and subsequent measurement. Economic analysis suggested that the brief intervention led to no statistically significant changes in subsequent health service resource use relative to standard treatment. CONCLUSIONS The brief intervention evaluated in this trial had no effect over standard advice delivered by nurses in primary health care. However, there was a reduction in excessive drinking across both arms of the trial over time. Due to nurse drop-out, this trial was significantly underpowered. Future research should explore barriers to nurses' involvement in research trials, particularly with an alcohol focus. A larger trial is required to evaluate the effectiveness of nurse-led screening and brief alcohol intervention in primary care.