Efforts to bring antiretroviral treatment to AIDS patients in developing countries are threatened by the looming implementation of new World Trade Organisation's patent rules, the charity Médecins Sans Frontières warned this week. The organisation's TRIPS (trade related aspects of intellectual property rights) agreement comes into force for most signatories on 1 January 2005. It requires the organisation's members to grant 20 year patents to new pharmaceutical products. Only the least developed countries can postpone implementation until 2016.