In the present study, fretting fatigue behavior of a Ti-6Al-4V alloy under high stress ratios in the ultra high cycle regime (up to 109 cycles) has been investigated. The slope of S-N curve decreased with increasing stress ratio. The slope was steeper in short fatigue life region and became flatter in longer life region. The test results under various stress ratios followed the modified Goodman diagram for both the fatigue strengths defined at 107 cycles and 108 cycles. The so-called non-propagating cracks, which were often observed in steels and aluminum alloys, could not be found in the run-out specimens tested up to 107 cycles. In the further loading cycles up to 109 cycles at the same stress amplitude, no crack initiation and propagation could be observed, which indicated that the conventional fretting fatigue strength defined 107 cycles was still effective at least up to 109 cycles. Different behavior between the titanium alloy used and the other materials mainly results from the different crack initiation behavior.