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PROP sensitivity varies greatly among individuals and can strongly influence food choice and satiety. It is associated with the bitter receptor gene (TAS2R38) and with differences in the salivary proteins involved in taste function. Among them, the enzyme Zn dependent gustin, a trophic factor of taste buds. We investigated the possible association of PROP taste phenotype with TAS2R38 haplotypes, gustin gene polymorphism rs2274333 (A/G), salivary Zn2+concentration and BMI. BMI were determined in 76 volunteers (29 males, 47 females, age 25 ± 3 y). PROP phenotype was determined by scaling methods and threshold measurements. The salivary Zn2+ concentration was determined and molecular analysis of TAS2R38 and gustin gene polymorphisms were performed using PCR techniques. PROP threshold determination can discriminate tasters from nontasters, while scaling methods distinguish also medium tasters from supertasters. Salivary Zn2+ and BMI were greater in nontasters than in supertasters. Molecular analysis of gustin DNA showed that allele A were more frequent in supertasters, while allele G were more frequent in nontasters. The lowest responsiveness in nontasters is strongly associated to AVI nontasting variant of TAS2R38, while the highest responsiveness in supertasters is strongly associated to allele A of gustin gene. The two genes account for up to 60% of phenotypic variance in PROP bitterness and to 40% in threshold values. These data demonstrated that sensitivity to PROP is inversely related to BMI and salivary Zn2+ and directly associated with the dimorphism rs2274333 in gustin gene that is hypothesized to affect its function. In addition, showed how the combination of TAS2R38 and gustin gene genotypes modulate PROP phenotype providing an additional tool for the evaluation of human eating behaviour and nutritional status.