In North America, clay bricks are qualified as durable if they meet either the ASTM C216 or CAN/CSA A82.1 standard. Although these standards are widely used in North America, they have not been linked with pore Structure (PS). Furthermore, moisture content and pore structure (PS) are two significant parameters that influence the performance of clay bricks during the freezing-thawing process. Thus, finding a relationship between them will lead to a quick assessment of water absorption (WA) and knowing their effect on frost resistance (FR). This work aims to investigate the relationship between PS and WA of clay bricks. Five different types of clay bricks were examined. WA of brick samples was determined according to the CAN/CSA A82.1 standard. Mercury Intrusion Porosimetry (MIP) was used to determine the total porosity and pore size distribution (PSD). The variation of 24-h cold water absorption (CWA) among samples of each type of brick was analyzed and each type of brick was divided into three groups according to their 24-h CWA: low - medium - high. The PSD of bricks was also divided into several ranges based on the pore size. The results indicated that some types of brick have a wide variation in 24-h CWA, which could affect the frost resistance evaluation. The strong relationship between WA and PSD was found, which could be used as a base for determining 24-h CWA.