Indonesia has the highest number of confirmed human H5N1 cases, but much evidence suggests the official numbers represent a gross under-count. The case fatality rate in Indonesia is around 80% and has been at that level since the first human case was confirmed 3 1/2 years ago. However, many patients are treated late in Indonesia, which increase case fatality rates, and many patients treated early test negative on Ministry of Health assays. Therefore the virulence of H5N1 in Indonesia is unclear.