The impact of an unstable hydrological regime on macroinvertebrates in an intermittent stream (with periodic summer droughts in particular stretches) was investigated in two successive years with differing climatic conditions. Ten series of macroinvertebrate samples were taken from two sampling sites between April 2002 and October 2003. Total abundance, taxa richness, main faunal groups, and life strategies were assessed in order to describe the changes in the macroinvertebrate assemblages. Periodic dry periods caused a decrease in macroinvertebrate density in the intermittent stretch, whereas they had no negative influence on number of taxa. Before the drought, the density of permanent fauna decreased and the number of r-strategists rose and stayed at a high level in first samples in the after-drought period. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)