Primers have been reported to increase adhesion between silicone elastomers and polyurethane liners used for maxillofacial prostheses. This study evaluated two primers, three polymerization methods, and seven primer reaction times to determine the conditions for optimum adhesive bond strength. The T-peel strength of specimens was determined as described in ASTM Standard D 1876-72. Failure modes were evaluated, and two-sample t tests and one-way ANOVA were used to compare means for significant (P .05) differences. Bond strengths were significantly greater for polyurethane treated with primer 1205 rather than S-2260 regardless of the polymerization method or primer reaction time. Neither any single polymerization method nor single primer reaction time consistently yielded greater bond strengths.