Purpose: The healing process following tooth extraction apparently results in a pronounced resorption of the alveolar ridge. As a result, the width of alveolar ridge is reduced and severe alveolar bone resorption occurs. The purpose of this experiment is to clinically and histologically evaluate the results of using horse-derived bone mineral for socket preservation. Methods: The study comprised 4 patients who were scheduled for extraction as a consequence of severe chronic periodontitis or apical lesion. The extraction was followed by socket preservation using horse-derived bone minerals. Clinical parameters included buccal-palatal width, mid-buccal crest height, and mid-palatal crest height. A histologic examination was conducted. Results: The surgical sites healed uneventfully. The mean ridge width was $7.75{pm}2.75;mm$ at baseline and $7.00{pm}2.45;mm$ at 6 months. The ridge width exhibited no significant difference between baseline and 6 months. The mean buccal crest height at baseline was $7.5{pm}5.20;mm$, and at 6 months, $3.50{pm}0.58;mm$. The mean palatal crest height at baseline was $7.75{pm}3.10;mm$, and at 6 months, $5.00{pm}0.82;mm$. There were no significant differences between baseline and 6 months regarding buccal and palatal crest heights. The amount of newly formed bone was $9.88{pm}2.90%$, the amount of graft particles was $42.62{pm}6.57%$, and the amount of soft tissue was $47.50{pm}9.28%$. Conclusions: Socket preservation using horse-derived bone mineral can effectively maintain ridge dimensions following tooth extraction and can promote new bone formation through osteoconductive activities.