BACKGROUND AND OBJECTIVE: Deciding about treatment goals at the end of life is a frequent and difficult challenge to medical staff. As more health care institutions issue ethico-legal guidelines to their staff the effects of such a guideline should be investigated in a pilot project.¦PARTICIPANTS AND METHODS: Prospective evaluation study using the pre-post method. Physicians and nurses working in ten intensive care units of a university medical center in Germany answered a specially designed questionnaire before and one year after issuance of the guideline.¦RESULTS: 197 analyzable answers were obtained from the first (pre-guideline) and 251 from the second (post-guideline) survey (54 % and 58 % response rate, respectively). Initially the clinicians expressed their need for guidelines, advice on ethical problems, and continuing education. One year after introduction of the guideline one third of the clinicians was familiar with the guideline's content and another third was aware of its existence. 90% of those who knew the document welcomed it. Explanation of the legal aspects was seen as its most useful element. The pre- and post-guideline comparison demonstrated that uncertainty in decision making and fear of legal consequences were reduced, while knowledge of legal aspects and the value given to advance directives increased. The residents had derived the greatest benefit.¦CONCLUSION: By promoting the knowledge of legal aspects and ethical considerations, guidelines given to medical staff can lead to more certainty when making in end of life decision.