SUMMARY.A new sampler is described combining the advantages of both box and Surber samplers. The sample area is 200 × 250 mm (0.05 m2) and the device has been used to sample the benthos of rivers to a depth ofc. 60 mm where the substratum consists of particles with diameters of 50 mm or less. The basic design may be used in water up to 0.5 m in depth, but with an optional top unit this depth may be increased to 1 m. Aquatic macrophytes can also be sampled either on their own or together with the underlying substratum. Results from sampling programmes designed to estimate macrophyte biomass, the biomass of the macroinvertebrate community and the density ofGammarus pulexare given as examples of the flexibility of the sampler on a variety of biotopes