A laser light scattering technique was assessed for measuring the microaggregate size distribution (MSD) of three Italian soils after water dispersion and after disaggregation with ultrasound. MSD values were unaffected by the amount of sample in the dry weight range from 0.05 to 2.0 grams. Some disaggregation of water‐treated samples may occur in the measuring system, so an appropriate measurement time has to be selected.