OBJECTIVE: To evaluate whether the quality of reporting harms improved after the publication of the Extension of the Consolidated Standards of Reporting Trials (CONSORT) statement and predictors that influence the safety reporting in randomized controlled trials (RCTs)STUDY DESIGN AND SETTING: Systematic survey of published RCTs assessing drugs. In MEDLINE, we identified 228 RCTs published in Annals of Internal Medicine, British Medical Journal, Journal of American Medical Association, The Lancet, and The New England Journal of Medicine in 2003 and 2006.RESULTS: The reporting of harms have improved over time both in quality and extent of space. However, the mean score as an overall measure of adequacy in reporting harms was 0.58 in 2003 and increased to 0.67 in 2006, indicating a moderate safety reporting. Safety was more adequate in trials with statistically significant results for efficacy, private funding, primary harms outcome, and anti-infective, antineoplasmatic, or immunosuppressive agents.CONCLUSION: The use of the Extension of the CONSORT statement may be associated with improving the quality of safety reporting in RCTs, but there are still deficiencies that need to be corrected to use quantitative objective evidence for harms in performing meta-analyses and making therapeutic decisions.