In the past two decades new practice parameters for clinical care in ALS were developed and several clinical trials were performed. We sought to review information in these prospective datasets and assess whether natural history of ALS has changed over time. Survival and the rate of functional decline were compared across the placebo arms of efficacy trials conducted from 1999 to 2005 by the Northeast ALS Consortium (NEALS). Similar data from the placebo arms of 12 other published efficacy ALS trials conducted between 1990 and 2008 were compared descriptively. In the three NEALS clinical trials, survival improved over time in the placebo cohort (p=0.05) while the rate of change in maximum voluntary isometric contraction (MVIC) (p=0.15), ALS Functional Rating Scale (ALSFRS) (p=0.6) and vital capacity (%VC) (p=0.5) was unchanged. No differences were observed in the mean rates of decline of these outcome measures in the published clinical trials. However, survival improved in the more recently conducted trials. Survival improved over time in placebo controlled participants enrolled in clinical trials in ALS since 1990. However, the decline in measures of function appears unchanged since then. These changes in natural history reflect improvements in symptomatic care of ALS.