Rutile containing Ni gives an internal-friction peak centered near 50°C at 2 kHz characterized by an activation energy E=15.3+/-2.4 kcal/mole and a characteristic relaxation time τ0=3×10-15+/-1.7 sec; this peak occurs for tensile stress along  or . A peak centered near 200°C with E=21.4+/-2.1 kcal/mole and τ0=8×10-15+/-1.0 sec occurs for stress along  but not for stress along . Rutile containing Cr gives similar peaks characterized by E=13.5+/-2.4 kcal/mole and τ0=2×10-14+/-1.6 sec and by E=22.2+/-1.5 kcal/mole and τ0=4×10-15+/-0.9 sec. Light reduction in vacuum decreases the amplitude of the low-temperature peak and enhances the high-temperature peak in both cases. Heavy reduction of rutile containing Cr removes both peaks but they reappear upon subsequent reoxidation. The evidence suggests that the motion of interstitial cations is involved and that reduction causes the formation of a compound defect. A tentative interpretation is given in terms of unpaired Ni3+ interstitials for the low-temperature peak and of interstitial pairs composed of Ni3+-Ti3+ for the high-temperature peak in Ni-doped specimens; the corresponding peaks in Cr-doped rutile are tentatively interpreted in terms of Ti4+ interstitials and of interstitial pairs consisting of Ti4+-Ti3+. It is possible to have two charge-compensating Cr3+ on adjacent substitutional sites and preserve the last two models.