The distribution of groove patterns and the presence of the hypoconulid on the first and second permanent lower molars of 1010 Icelanders from one urban and two rural populations was determined from dental stone casts. There was considerable modification of the ancestral Y-pattern, as expected in a Caucasoid population. Neither the sexes nor the subpopulations showed significant differences in the groove patterns. The absence of the hypoconulid on the first molar was significantly more common in women than in men, and there was also some evidence of differences between the subpopulations. On the whole, the lower molar pattern of Icelanders was within expectations.