The Consolidated Standards for Reporting of Trials (CONSORT) statement was developed to improve the quality of randomized controlled trial (RCT) reports. We assessed the quality of current Japanese RCT reports by conducting a cross-sectional study to examine the extent to which they adhere to the CONSORT statement. Reports of RCTs conducted in Japan that were published in medical journals between January and March 2004 were sampled from MEDLINE. The proportion of adherence to each item in the CONSORT checklist was evaluated for each report. Additionally, information on ethics reporting and funding sources was collected. A total of 98 RCT reports from Japan were evaluated, and adherence to the CONSORT statement was found to be suboptimal. Only 6 of 29 items in the checklist were described in more than 80% of reports. Adherence to key methodological items of the CONSORT statement was as follows: 23% for sample size determination, 39% for random sequence generation, 17% for allocation concealment, 29% for blinding, 53% for numbers analyzed, and 6% for inclusion of a flow diagram. Adherence to additional items was 82% for ethics committee approval, 92% for receiving informed consent, and 20% for disclosing funding sources. Our study on adherence of recent RCT reports from Japan to the CONSORT statement reveals that there is a significant need for improvement. Further investigation on the quality of RCT reports and ways to improve reporting quality is required.