Objective To investigate the report rate of ethical review in registered Chinese trials records.

Methods Chinese trials recorded in WHO primary registries and http://clinicaltrials.gov to 14 July 2009 were identified. The report rates of ethical review and each of the 20 items in WHO's Trial Registration Data Set were calculated. Correlation of the item's report rate with the ethical review report rate was assessed. PubMed, EMBASE, CNKI and CBM (from the establishment of each database to 14 July 2009) were also searched to collect the full texts of completed trials to calculate the report rate of ethical review in the result publications.

Results A total of 1247 records were identified, and 687 (55.1%) reported ethical review. The records reporting secondary sponsor(s), contact for public queries and key secondary outcomes were more likely to report ethical review information (66.3% vs 44.3%, 38.1% vs 28.5%, 53.9% vs 51.8%). The ethical review report rate of trials sponsored by industry was lower than those sponsored by non-industry (40.9% vs 51.9%). The report rates of ethical review for self-supported trials (83.5%) and trials with unidentified sources of monetary or material support (66.7%) were lower than the average ethical review report rate for records in the Chinese Clinical Trial Registration Center (ChiCTR). The ethical review report rate was not high in the result publications (84.3% in http://clinicaltrials.gov, 50.0% in ChiCTR).

Conclusion Registered Chinese trials records report ethical review inadequately. Incomplete registration is correlated with not reporting ethical review. Medical journals should inspect ethical review more critically.