The transition from mild to severe wear mechanism of Ti-6Al4V alloy was investigated. Microstructure and wear micro-mechanisms 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 aresignificantly 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.