We present a comparison of calculated and measured orientation-dependent electron-energy-loss spectroscopy (EELS) spectra of TiO2. The measurements were carried out with a scanning transmission microscope equipped with a parallel EELS detector. The lateral resolution is about 1 nm and the energy resolution is about 0.3?0.4 eV. The calculations are based on density functional theory. Spin-orbit coupling is included in the theoretical description of the core levels. Many-body corrections are included by a Z+1 approximation. The influence of experimental parameters like the collector and divergence semiangles are discussed in detail. Very good agreement between theoretical and experimental results concerning the peak positions of the spectra is reached by means of the Z+1 approximation. The investigated rutile, anatase, and brookite modifications exhibit pronounced differences in the L3 edge of titanium. The orientation dependence is clearly visible in the oxygen K edge.