The article introduces a special report on the most important medical achievements of 2005. The author suggest that the veterinary scientist Woo Suk Hwang of Seoul National University made the biggest medical news of the year. Hwang and his 45-person team became the first to use cloning techniques to create stem cells from human patients suffering from diseases such as diabetes and spinal cord injury. Also discussed is the recent controversy surrounding Hwang's work, which resulted in his resignation from a new stem-cell research center.