A constitutive equation is proposed to characterize the viscoelastic properties of wet human compact bone measured in torsion at body temperature. The equation is developed, using a spectrum of relaxation times, H(τ)=logτ τ₁≤τ≤τ₂, 0 τ<τ₁,τ>τ₂ called the ‘triangle’ spectrum. The transient and dynamic viscoelastic moduli are derived from this. Applications of this distribution to other viscoelastic data as well as to dielectric systems, are discussed. Nonlinear effects observed in bone are described using the first two terms of a multiple-integral expansion. The dynamic properties of two types of nonlinear solid are obtained from constitutive equations based on transients, and applications to bone mechanics are discussed.