We investigate by analytical means the electronic transport properties of approximants and quasicrystals. The spectral resistivity is modeled by Lorentz functions in agreement with realistic ab initio calculations (linear muffin-tin orbital basis, Kubo-Greenwood formula) for low-order approximants. The analytical expressions for the transport coefficients compare well with both numerical calculations and experiments. Thus, the temperature-dependent conductivity, thermopower, electronic thermal conductivity, and Lorenz number of certain approximants and quasicrystals can be consistently explained. © 2003 The American Physical Society.