Little quantitative data exist concerning use of intermittent streams by crayfishes.  We documented use of an intermittent stream by two imperiled crayfishes, and determined their response to stream drying.  In 2003 we discovered Orconectes williamsi and Orconectes m. meeki, in Rock Creek, Barry County, Missouri, U.S.A.; later that summer this stream reach dried.  During 2005 we measured (quadrat) crayfish densities for 10 riffles (June), and measured wetted area (m²) for each riffle (July-August). During May-August 2006 we repeated monthly crayfish density, wetted area and current velocity measurements.  When riffles dried, we excavated quadrats 30 cm deep to locate crayfish.  During both years riffles dried significantly by July; by August most riffles had no surface flow.  June densities of O. m. meeki were slightly lower in 2006 (4.3/m² +0.8 SE) than 2005 (7.1+1.4), but O. williamsi densities remained stable (11.8+2.4, 2005; 12.2+2.0, 2006) suggesting that previous summer drying did not affect their numbers.  Adult O. meeki and O. williamsi densities increased from May to June 2006, then decreased in July/August, possibly because crayfish burrowed deeper in dry riffles than we searched.  Many crayfish (O. williamsi = 5.1-5.2/m², O. m. meeki = 2.0-6.0/m²) used the hyporheic zone in "dried" riffles in July/August.