In spite of the wide variety and complexity of biological materials, nucleic acids are ubiquitous. DNA is becoming the bioanalyte of choice due to the vast amount of information embedded in its sequence, its robust chemical nature and the range of highly sensitive analytical techniques that have been developed. The results of such analyses can have an important impact on our society both commercially and in terms of the quality of life. Absolute confidence in the data generated is therefore of the utmost importance. This book, produced by the LGC as part of the valid analytical measurement (VAM) programme, introduces the issues of validation and quality to the bioanalytical community, specifically addressing DNA-based analyses. It aims to raise awareness of the factors that can influence the validity of DNA analysis and the production of quality data. Emphasis is placed on VAM principles, as well as additional challenges that are associated with the analysis of real samples, for example, complex food matrices or forensic samples that have been subjected to environmental insult. Information is collated from a variety of sources including literature, discussions and LGC research, and constructive advice is offered where possible.