Objectives: To evaluate the distribution of morphologic types of subgingival calculus at different parts of the proximal root surface. Method and materials: Ninety extracted teeth from 29 chronic periodontitis patients were collected. The mean pocket depths and periodontal attachment levels of the extracted teeth were 5.93 ± 1.51 mm and 7.82 ± 1.75 mm, respectively. The proximal root surfaces below the gingival margin were divided into three parts in an apicocoronal direction, and each of these portions was further divided into three parts in a buccolingual direction. Subgingival calculus present was classified as: 1 = crusty, spiny, or nodular; 2 = ledge or ring; 3 = thin, smooth veneers; 4 = finger- or fernlike; 5 = individual calculus islands/spots; or 6 = supramarginal upon submarginal deposits. The distribution of different morphologic types of subgingival calculus on each division of the mesial and distal proximal root surfaces was evaluated with a magnifier. Results: Regardless of the morphologic type, calculus deposits were observed at around 30% of proximal root surfaces. The coronal thirds of the root surfaces were found to have significantly more calculus deposits than the middle thirds (P < .05). In general, it was observed that most of the deposits were of the thin, smooth veneer type on all root surfaces. Conclusion: Within the limits of this study, the distribution of various calculus types was similar on different parts of the root surface; however, calculus was found more frequently on the coronal thirds than on the more apical regions. (Quintessence Int 2005;36:202–208)