Gattinoni (Milan, Italy) presented the results of the longawaited Italian multicentre randomized controlled trial of prone positioning in ARDS (unpublished data). This trial was terminated after 3 years despite having only recruited 304 patients; enrollment of 750 patients was originally planned, in order to achieve sufficient statistical power. At trial outset, recruitment was encumbered by the lack of familiarity with and scepticism regarding this procedure in many of the centres. However, by the end of the study many participants were unwilling to enter patients into the trial, because they felt it unethical to deny them this intervention. The trial protocol resulted in patients in the treatment group being prone for an average of only 7 out of 24 h for a 10-day period. Overall there was no difference in mortality between the control and treatment groups at day 10, time of ICU discharge, or at 6 months. Interestingly, analysis of subgroups revealed a significant difference in the outcome at 10 days for patients with the most severe disease, although this disappeared by ICU discharge. In retrospect, the design of this ambitious trial was flawed by its failure to establish the optimal utilization of this manoeuvre. 