The breakdown strength of rutile crystals has been measured ∥ and ⊥ to the optic axis. The dc breakdown is a thermal process occurring at a power level of 2 kw/cm3for the particular sample size and test cell used here, with field strengths of 20 kv/cm ∥ to the axis and 120 kv/cm ⊥. Impulse measurements at 1‐&mgr;sec rise time required special techniques of sample and electrode preparation in order to prevent field distortion and surface breakdown. Breakdown strengths of 570 kv/cm ⊥ and 690 kv/cm ∥ to the optic axis were measured.