Oxygen was introduced into a single crystal of titanium in successive stages. The intensities of the h00 and 00l reflections were measured with a single-crystal diffractometer. The observed variation of the intensities with oxygen concentration was attributed to three factors: (1) the additional scattering from the oxygen atoms, (2) a change in the Debye-Waller factor, and (3) an exponential factor originating from the distortion around the oxygen atom. The theory of X-ray scattering from crystals containing centers of distortion was applied to the hexagonal titanium containing interstitial oxygen atoms. Using the variation of the lattice constant with oxygen concentration, it was possible to predict the intensity reduction due to lattice strains. It was concluded that it would have been possible to obtain an estimate of the defect concentration from the X-ray measurements of lattice expansion and intensity reduction.