This is a compelling book by one of the most trenchant historical writers of his generation. Hamlin's central contention is that “in many ways cholera is what it was in 1830” (p. 268). This assertion is rooted in an overview of changes in scientific thought since the 1990s; research which asserts that the infection may never, contrary to orientalizing ideology, have been an “Asian” export; that, following remission, epidemic recrudescence may occur through the medium of unstable organisms living in warm sea (and river?) water; and that the disease, however defined, bears striking similarities to a bewildering range of anciently established diarrhoeal conditions. Finally, many contemporary specialists agree that epidemics are as likely to be triggered by seasonal and environmental change as the movement of disease-carrying individuals into infection-free communities. The centrality of the faecal-oral route is downplayed. In places, Hamlin gives too little space to the fine detail of ongoing debate. Thus his overview would have been strengthened by reference to Paul W Ewald's article in Epidemiology and Infection in 1991 and the same author's comments in his Evolution of infectious disease (1994) on the appalling problems faced by Bangladesh, a country to which Hamlin himself gives brief mention (pp. 272–4). On balance, however, this is a superb survey of an exceptionally difficult body of knowledge and controversy, shaped by a move away from medical-cum-epidemiological modelling and towards ecological and global variables. Does this radical shift in emphasis, which sub-textually dominates Hamlin's book, invalidate the findings of the great wave of cholera studies produced between the early 1960s and the early 1990s, and those contained in the torrent of colonial and post-colonial research undertaken over the last twenty years? Probably not. The most impressive medico-demographic publications have scrutinized the ways in which nineteenth-century medical men and health officials used a wide range of categories and subcategories—diarrhoea, infant diarrhoea, choleraic diarrhoea, dysentery and cholera—to differentiate between the myriad gut diseases that lurked in their midst. Other authors creatively focused on the cholera phenomenon, as Asa Briggs urged them, to clarify social, political and urban power relations. Yet others concentrated on epidemic catastrophe to chart the development of public water supply systems and, in Britain, the rise of Chadwickian sanitarianism. (Hamlin, who has written with distinction about the great health dictator says little about him in this study. However, the main tenets of nineteenth-century sanitary science are expertly summarized and interrogated in a subsection on ‘Positions and paradigms’ [pp. 152–9].) The new agenda demands that historians concentrate on “non-crisis” years in which medical men nevertheless recorded significant numbers of individuals perishing from cholera and choleraic diarrhoea. With European-centred work in this area at a low ebb, the task might rekindle the fire. Thirty years ago, the present reviewer urged historians to use under-exploited epidemiological sources retrospectively to diagnose localized patterns of cause-specific mortality from cholera, diarrhoea, dysentery, typhoid and typhus. Today that programme seems over-ambitious and over-positivistic: more rewarding, as Hamlin so powerfully implies, to trace continuities and discontinuities in archaeologies of cholera knowledge— regardless of what the condition indisputably “is” or may have “been”—from the humoral to the ecological. This book undermines the linearity of “biography”, creatively deconstructs and subverts its own subject-matter and asks fundamental questions about connections and disruptions between past and present. Hamlin's study appears in a series designed to be read by the widest possible audience. Medical historians cannot afford to ignore so excellently written a provocative account of what needs to be done next.