In England & Wales at least 140 000 people present at hospital annually following an episode of deliberate self-harm (DSH), and 12% to 16% make a repeat attempt. The time of greatest risk of repetition is within three months of an attempt. Around 50% of these patients visit their GP in the four to eight weeks after an episode of DSH. Guidelines for the aftercare of patients who have self-harmed in general practice may reduce repetition rates and could possibly have an impact on suicide rates. The aim of this study was to develop a clinical practice guideline for the aftercare of DSH patients in general practice. A modified Delphi technique was used with a consensus group consisting of GPs with an interest in mental health, psychiatrists, a psychologist, a specialist nurse, a voluntary organization and patients with a history of self-harm. The template for the guidelines was based on ICD-10 PHC. Consensus was reached on all points after two rounds of the Delphi and the guidelines were formatted to facilitate their use in the GP consultation. There is a difficulty developing guidelines for common problems where the evidence base is weak. The use of formal consensus methods can be employed but it must be acknowledged that the validity of the resulting guideline is related to the composition of the consensus group, the identification and analysis of any relevant evidence and the method of guideline dissemination. The guidelines are being evaluated in a randomized controlled trial of a general practice based intervention to reduce repeat deliberate self-harm.