In 2003, under the auspices of the main UK funders of biological and biomedical research, a working group was established with a remit to review potential welfare issues for genetically altered （GA） mice, to summarize current practice, and to recommend contemporary best practi.ce for welfare assessments. The working group has produced a report which makes practical recommendations for GA mouse welfare assessment and dissemination of welfare information between establishments using a ＇mouse passport＇ . The report can be found at www. nc3rs, org. uk/GAmice and www. lal. org. uk/gaa and includes templates for the recommended welfare assessment scheme and the mouse passport. An overview is provided below.