It is well-established that the bonding strength between resin and acid-etched enamel is considered clinically adequate. The tensile bonding strength mediated by a group of dentinal bonding agents (DBA's) to both dentin and acid-etched enamel was measured after one hour and the results compared. For all the DBA's tested, the bonding strength to enamel was higher than that to dentin. These differences were significant for all DBA's except for Gluma/Clearfil F-II. Analysis of variance revealed significant differences between material-specific means to either enamel or dentin. For enamel, the significant differences were due to relatively low bonding strength value measured with the Prisma Bond. The bonding strength of all DBA's tested to acid-etched enamel would secure clinically high retention rate and adequate marginal quality. For dentin, these differences were due mainly to the high mean values for strength of bonds when the Gluma/Clearfil F-II combination was used. The low values and the large variations of the bonds to dentin measured with the commercial systems would affect the two major functions of DBA's, namely, retention of the restoration and prevention of marginal gaps. The Gluma/Clearfil combination should be recommended for clinical trials.