Almost a decade has passed since the first edition of this book was published and the explosion of new research in stroke is very apparent. Several important themes have coloured medicine during this time: the development of evidence based health care, new optimism for acute drug treatments for stroke, the growth of new information about the human genome, a dramatic increase in the number of stroke clinicians and researchers world-wide, and the establishment of the Cochrane Collaboration. All of these trends are relevant in revising a book of this nature. Clinical epidemiology remains an essential foundation for the practice of evidence-based healthcare. The enthusiasm of the pharmaceutical industry has resulted in a large number of new trials, often too small to detect clinically important differences, and have increased the number of clinicians actively engaged in stroke research. It is even more important that these clinicians should have a good understanding of the design of trials, the rationale for randomisation and blinding, and the importance of selecting the most appropriate outcomes. Surprisingly, little of practical importance has resulted from the decade of exploration of the human genome - the best indication of a person's risk remains their phenotype and not their genotype.