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Benthic invertebrates were quantified in 6 small upland streams in Alabama for 2 y to examine the degree to which variation in assemblage structure was related to the hydrologic permanence of riffle habitats. Streams differed along a gradient of flow permanence: 2 were normally intermittent (i.e., riffles ceased flowing in normal rainfall years) in summer, 1 was rarely intermittent (i.e., normally perennial), and 3 streams were occasionally intermittent (i.e., riffles ceased flowing during dry years). Despite large differences in flow permanence among streams, invertebrate assemblages differed only slightly. Presence-absence data revealed that 75% of the species (171 total taxa, predominantly aquatic insects) were ubiquitous across the 6 streams or displayed no pattern with respect to permanence; 7% of the total species were found exclusively in the normally intermittent streams. Although somewhat variable, many of the community richness and diversity measures were positively correlated with stream permanence. Year-to-year differences in assemblages within single streams appeared as great as differences between streams of contrasting permanence within a given year. Faunal similarity among streams was higher in 1995, a year with normal summer rainfall that followed a wet year (1994), than in 1994, a wet year that followed a dry year. Between-year differences in density and richness were lowest in spring and winter and greatest in summer, the season when communities were directly exposed to drying of riffles in intermittent streams. Several populations of common invertebrates during summer displayed non-random distributions along the permanence gradient. These data in general support the hypotheses that 1) benthic invertebrate assemblages show predictable, albeit subtle, relationships with stream permanence, and 2) antecedent hydrologic conditions associated with riffle permanence, perhaps because of their effects on survival and recruitment of subsequent generations, can influence the structure of benthic assemblages in streams.