Purpose: To evaluate the histologic response of 332 non-exposed and 127 exposed monkey pulps applying nine adhesive systems. Materials and Methods: Class V and Class I cavities were used in non-exposed and exposed monkey pulps at the three ISO usage time intervals. Results: There were no histologic differences in pulp responses among the nine adhesive systems used in either Class V and/or Class I cavities when compared to pulp responses of Ca(OH)(2) controls at the ISO time intervals. The nine adhesive systems and resin composites are non-toxic to either non-exposed or exposed pulps, being biologically compatible to pulp tissues when placed on mechanical pulp exposures following hemorrhage control with a 2.5% NaOCl and per manufacturers' directions. It is imperative that clinicians understand the biological importance of hemorrhage control as well as the technique sensitivity of hydrophilic primers in order to optimize the efficacy of adhesives for clinical success against microleakage of bacterial factors.