We report results on the electronic, vibrational, and optical properties of SnO2 obtained using first-principles calculations performed within the density functional theory. All the calculated phonon frequencies, real and imaginary parts of complex dielectric function, the energy-loss spectrum, the refractive index, the extinction, and the absorption coefficients show good agreement with experimental results. Based on our calculations, the SnO2 electron and hole effective masses were found to be strongly anisotropic. The lattice contribution to the low-frequency region of the SnO2 dielectric function arising from optical phonons was also determined resulting the values of ɛ 1⊥ latt (0) = 14.6 and ɛ 1∥ latt (0) = 10.7 for directions perpendicular and parallel to the tetragonal c-axis, respectively. This is in excellent agreement with the available experimental data. After adding the electronic contribution to the lattice contribution, a total average value of ɛ1(0) = 18.2 is predicted for the static permittivity constant of SnO2.