Forty maxillary and four mandibular first premolars that were to be extracted for orthodontic reasons were used in this study to evaluate human pulpal response to hydroxyapatite and Dycal as direct capping materials. After the postoperative periods of 2 days, 30 days and, 60 days, teeth were extracted and prepared for the histologic examination. The results of this study showed that hydroxyapatite does not induce hard tissue bridging at the exposure site in human dental pulp. No hard tissue bridging at the exposure site was observed in any of the teeth capped with hydroxyapatite. Moderate infiltration of the inflammatory cells was seen generally in the teeth capped with hydroxyapatite. However, this study has verified that exposed human dental pulp will heal under Dycal application with hard tissue bridging and with none or minimal inflammatory response.