Introduction: Intercessory prayer (asking God - regardless of specific theology - to intervene and transform or resolve the situation of another) is a widely used intervention for those in any kind of need.

Objective: To investigate the effectiveness of organised intercessory prayer for those suffering from ill health of any kind. It is not the intention of this study to prove the existence or otherwise of God - or even that, if God exists, he answers such prayers - or to focus on any one particular faith, but simply to evaluate the extent to which prayer, the intervention, produces measurable results. The fact that there may be a strong psychosomatic effect of prayer and that this might be quantifiable makes this investigation both possible and important.

Methods: Systematic review of randomized controlled trials. Trials were located from searches of commercial databases and reference lists. Independent selection and data extraction from trials was performed by at least two reviewers. Where possible the results were summated. Methodological limitations: The reviewers anticipate that, for this particular review, potential limitations of RCT methodology may confound results. God may be omnipotent and therefore not randomizable, and in certain instances has specifically requested that He/She not be trialed. Further problems arise within any individual trial as a result of 'contamination' of the non-prayer group by those praying for individuals outside the remit of the trial.

Results/Discussion: This review is ongoing. Results and conclusions will be available by the end of May 1997 and presented first at the Amsterdam Colloquium.