The recent history of clinical trials in ALS is marked by a great diversity in trial design. This has limited the comparability of the trial results, and has resulted in intense discussions about which parameters should or should not be evaluated when testing a new drug for ALS. This article discusses, without any claim to completeness, some aspects of trial design in relation to past, ongoing and future ALS trials, including: choice of endpoints, measurement of disease progression, assessment of quality of life, placebo-controlled trials, open-label trials, collaboration with the industry, and methods for investigating mechanisms of action of experimental drugs.