The transition from mild to severe wear mechanism of Ti-6Al4V alloy was investigated. Microstructure and wear micromechanisms were also investigated. The as-cast samples were subjected to hot swaging at 900°C, followed by two separate solution treatments on the swaged samples. The first treatment was applied at a temperature of 850 °C (below the β-transus temperature) for getting a bimodal structure (α+β), while the second treatment was performed at 1050 °C (above the β-transus) for getting a lamellar structure (β). The solution-treated lamellar structure resulted in an ultimate strength of 1335 MPa and a hardness of 440 HV20 which are significantly superior to the bimodal structure. The wear behavior of the studied Ti64 alloy was investigated at different sliding speeds in the range of 0.5 to 2.5 m/s with 0.5 m/s interval. The transition from mild to severe wear mechanism was obtained at 1.5 m/s. The lowest wear rate was reported for the samples solution treated at 1050 °C due to their fine lamellae (α+β) structure and the high hardness. SEM was used to evaluate the worn surfaces of some samples to determine the wear micro-mechanisms.