This study demonstrates the use of the membrane filter technique for comparing hyphal abundance in grassland soils. The long-term removal of sheep grazing from an upland Agrostis-Festuca grassland has resulted in an increase in total hyphal lengths in the surface soil (1460 ± 159 and 2111 ± 152 mg-1 dry soil in the grazed and ungrazed treatments, respectively). Total to those obtained by other authors for a similar grassland using the agar film technique. The level of accuracy and flexibility and the labour savings associated with the preparation of films make the membrane filter technique particularly suitable for comparative investigations of different experimental sites. © 1991.