The dynamic shear moduli of human dentin and enamel were measured using a torsion pendulum over a temperature range from 23 to 150 degrees C. For dentin, the shear modulus slightly increased for temperatures near 50 to 100 degrees C, which was caused by a loss of free water. The peak in the loss tangent was observed near 75 degrees C. The shear moduli at 37 degrees C for sixty coronal dentin specimens ranged from 5.77 X 10(10) to 1.16 X 10(11) dyn/cm2. For enamel, the shear modulus and the loss tangent were markedly stable and independent of the temperature. The shear moduli at 37 degrees C for forty specimens ranged from 2.35 X 10(11) to 4.48 X 10(11) dyn/cm2. Enamel had a modulus which was approximately three to five times higher, and a lower loss tangent than those of dentin. For both dentin and enamel, there were no significant correlations between the values of the shear modulus and sex, age or tooth type.