Humans show substantial differences in taste sensitivity to many different substances. Some of this variation is known to be genetic in origin, and many other inter-individual differences are likely to be partially or wholly determined by genetic mechanisms. Recent advances in the understanding of taste at the molecular level have provided candidate genes that can be evaluated for contributions to phenotypic differences in taste abilities. This approach has provided an understanding of variation in the ability to taste phenylthiocarbamide (PTC), and has resolved long-standing controversies about the genetics of this classic human genetic trait. Significant coding sequence variation exists in taste receptor genes, which suggests that PTC tasting may indicate more general taste sensory variation. However, many aspects of taste perception remain poorly characterized. Better understanding of the molecular components of salty and sour tastes is still needed, as is a more complete picture of second messenger and downstream signaling mechanisms for all taste modalities. More general studies of linkage and association between genetic markers and taste phenotypes may reveal genes encoding proteins that were previously unsuspected to be involved in this sensory process.