Growth factors is one of recent development of pulp capping materials. Some research show that growth factors can accelerate the healing of injured tissue. Pulp of teeth can be exposed because of injury at the time of preparation due to operator error (iatrogenic), so direct pulp capping is needed. The direct pulp capping materials that used in this study is platelet rich plasma (PRP). The aim of this study was to evaluate nestin expression of pulp tissue following direct pulp capping with PRP. The thirty sound teeth from Sprague dawley rats were used and divided into two groups: groups 1, teeth were capped with calcium hydroxide/Ca(OH)2 (n=15) and group 2 with PRP (n=15). After 1st, 7th and 21st days respectively, 5 teeth each group (American Dental Association/ADA 41) were processed for light microscopic examination. Expressions of nestin were assessed by immunohistochemical techniques. The result, nestin exspression of Ca(OH)2 on the distance place of exsposure at 1st day and 7th days were 80% and at 21st days were 60%. Nestin exspression of PRP on the distance place at 1st day was 80%, 7th 100% and 21st days were 80%. At day 21 observation, Kruskal Wallis test show nestin exspression was increase significantly in PRP groups (p<0,05) but it was not increase significantly compare with Ca(OH)2 . Conclusion, PRP had ability as a direct pulp capping material to induce nestin exspression.