Clay-rich soils were sampled in the agricultural areas of Montreal, Quebec and Lake St-Jean. Undisrupted soil blocks and bulk samples were taken by horizon in the Ste-Rosalie, Kamouraska and Normandin soil series. Aggregate stability increased with the organic matter content. Bulk density was generally highest in the B horizons. Porosity ranged from 39 to 56% of the total soil volume and the most representative pore diameter varied from 0.706 to 0.048 μm with the largest diameter being found in the Ap horizons. The distribution of porosity among large, medium and small pores in the Ste-Rosalie soil differed from that in the Kamouraska and Normandin soils. In the former, medium pores accounted for only a few percent of total porosity, while the pores were more evenly distributed in the latter soils. Medium pore contents decreased, while small pore contents increased, with increasing clay contents. No significant relationship was observed between large pores and clay percentages. Hydraulic conductivity, with mean values ranging from 3.5 to 109.3 cm/h, was significantly related to the large pore class.