The denture prosthesis was still made by Investment Casting technique at present time. But this method had problems such as shrinkage and expansion which may result in deformation of the castings, especially for some large sized prosthesis. Meanwhile, fatigue fracture of denture prosthesis may take place due to stress after repeated insertion and removal as for clean up or under mastication. To fix the prosthetic fracture, laser-welding is recommended for Ti alloys. This study was to investigate the fatigue property of Nd : YAG laser-welded Ti-6Al-7Nb alloys in artificial saliva. Commercial cast Ti-6Al-7Nb alloy joints were proceeded to Nd:YAG laser welding (welding voltage: 310, 330, 350 V equivalent to energy: 11, 14, 17 J) for fatigue test. According to the present studies, fluoride ions may induce the corrosion of Ti joints. As most OTC oral hygiene products containing fluoride ions, besides in air and artificial saliva, the fatigue lives of Ti-6Al-7Nb joints were also evaluated in fluoride-containing (0.5% NaF) artificial saliva. The results showed that increasing Nd:YAG laser welding energy would increase the fatigue life of Ti-6Al-7Nb alloy; the average fatigue life of laser-welded Ti-6Al-7Nb alloy joints in air environment was higher than that obtained in both artificial saliva groups (with and without fluoride). And there was no significant difference between the fluoride-containing group and artificial saliva (without fluoride) group for fatigue life.