Changes in the macroinvertebrate community in response to flow variations in the Little Stour River, Kent, UK, were examined over a 6 year period (1992-1997). This period included the final year of the 1988-1992 drought, followed by some of the wettest conditions recorded this century and a second period of drought between 1996 and 1997. Each year, samples were collected from 15 sites during late-summer base-flow conditions. Correspondence analysis identified clear differences between samples from upstream and downstream sites, and between drought and non-drought years. Step-wise multiple regression was used to identify hydrological indicators of community variation. Several different indices were used to describe the macroinvertebrate community, including macroinvertebrate community abundance, number of families and species, and individual species. Site characteristics were fundamental in accounting for variation in the unstandardized macroinvertebrate community. However, when differences between sites were controlled, hydrological conditions were found to play a dominant role in explaining ecological variation. Indices of high discharge (or their absence), 4-7 months prior to sampling (i.e. winter-spring), were found to be the most important variables for describing the late-summer community The results are discussed in relation to the role of flow variability in shaping instream communities and management implications. Copyright ?? 2000 John Wiley & Sons, Ltd.Changes in the macroinvertebrate community in response to flow variations in the Little Stour River, Kent, UK, were examined over a 6 year period (1992-1997). This period included the final year of the 1988-1992 drought, followed by some of the wettest conditions recorded this century and a second period of drought between 1996 and 1997. Each year, samples were collected from 15 sites during late-summer base-flow conditions. Correspondence analysis identified clear differences between samples from upstream and downstream sites, and between drought and non-drought years. Step-wise multiple regression was used to identify hydrological indicators of community variation. Several different indices were used to describe the macroinvertebrate community, including macroinvertebrate community abundance, number of families and species, and individual species. Site characteristics were fundamental in accounting for variation in the unstandardized macroinvertebrate community. However, when differences between sites were controlled, hydrological conditions were found to play a dominant role in explaining ecological variation. Indices of high discharge (or their absence), 4-7 months prior to sampling (i.e. winter-spring), were found to be the most important variables for describing the late-summer community. The results are discussed in relation to the role of flow variability in shaping instream communities and management implications.