Samples from four surface and one subsurface horizons of clay-rich soils from Quebec were air-dried and critical point dried. In the latter samples, the total pore volume was 19–84% larger than in the former samples. The total pore volume, determined by mercury intrusion porosimetry and density measurements, was subdivided into large (> 8.8 μm), medium, and small (< 0.19 μm) pores. The effect of drying on these pores was estimated. Medium-sized pores were affected most by the drying technique, followed next by the large pores, and finally by the small pores. The modifications due to drying could not be explained adequately by shrinkage and it was assumed, from the pore-size distribution curves, that organic matter content had a buffer effect on particle reorganization. Keywords: critical point drying, clay soils, pore volume, pore-size distribution, organic matter.