The mechanical properties of samples made by 3D printing from poly(lactic acid) (PLA) and PLA filled with 20, 40, 60 and 80 wt% PLA/Al2O3 (85/15) was evaluated. Addition of PLA/Al2O3 improved mechanical properties of PLA. Tensile strength increased by approx. 19%, tensile modulus by 27%, compression modulus by approx. 42%, flexural modulus by 70%, impact strength by 20% and hardness by approx. 14% compared with pure PLA.