Systematic screening of patients for areas of health risk in their lifestyle has much potential for primary health care clinicians as a cost‐effective and time saving means to identify ‘at risk’ individuals. In the area of alcohol and drug problems, such early identification increases the likelihood of successful intervention. The present study, conducted at a general practice unit, compared the use of a computer to screen for alcohol and drug use with the two more traditional assessment methods of face‐to‐face interview and paper and pencil questionnaire. It was found that levels of reported consumption were similar across assessment methods. Although the interview method was strongly preferred overall, patients’ preference for the computer increased significantly after use. The computer was also found to be more acceptable to patients reporting non‐medical drug use, a potentially threatening and sensitive issue. There was a low refusal rate and most patients were willing to allow their doctor to see the assessment results. This indicates that screening for alcohol and drug use is acceptable to general practice patients, and that the computer can play a useful role as a prevention aid.