Japan's Ministry of Health and Welfare (MHW; Tokyo) announced at the end of January that it is considering revising guidelines to allow treatment of chronic diseases such as arteriosclerosis and rheumatoid arthritis with gene therapy. This would substantially expand the range of diseases that can be treated by gene therapy, which is currently restricted to serious life-threatening diseases such as AIDS and cancer. Although the current guidelines, drawn up in 1994, are based on similar guidelines issued by the US National Institutes of Health (Bethesda, MD), MHW decided to restrict the use of gene therapy because of initial safety concerns. But after reviewing safety data from clinical trials in both the US and Japan, the government has changed its mind, and new guidelines are expected by the end of the year.