Abstract Background: In 1994 consensus guidelines were developed for conducting clinical trials in ALS. With growing experience in clinical trials, it has become clear that a number of further guidelines were needed. Methods: Under the auspices of the World Federation of Neurology Committee on Research, a multinational group of neurologists, statisticians, patient advocates, representatives from the pharmaceutical industry as well as regulatory agencies developed consensus about a number of revisions to the existing guidelines during a 2 day conference in April 1998. Results: Expanded areas of focus include greater protection of patient rights, more detailed guidelines for outcome measures statistical analyses, disclosure of study results and improved interaction between investigators and the corporate sector. Comment: Substantial progress has been made in standardizing and improving the quality of clinical trials in ALS through these consensus guidelines.