Taste sensitivity to phenylthiocarbamide is thought to reflect a genotype homozygous for a single recessive gene. European and North American populations show a mean non-taster frequency of about 30% whereas Mongoloid populations show a much lower frequency of non-tasters. In the present study of Nigerians, there were mean non-taster frequencies of 1.9-2.9% among healthy subjects and not a significantly different level, 3.5%, among goitrous ones. Among subjects with nodular goiter, however, the non-taster frequency was 18.7%, significantly higher. The results suggest that there is a rarity of non-tasters among Nigerians and that non-tasters are more susceptible to the development of nodular goiter than are tasters.