Objective: The objective of this study was to investigate the effect of laser welding parameters (current [A], spot diameter [mm], and pulse duration [ms]) on the weld penetration depth by Nd:YAG laser into cast titanium and Ag-based and Au-based alloys. Method and Materials: Two cast blocks of each metal were laser welded with various parameters at their interface. The blocks were then separated, and the penetration depth into each metal was measured on the separated surface using a computer program. The data were statistically analyzed. Results: Increasing the current and decreasing the spot diameter increased the penetration depth into each alloy. No statistical differences in penetration depth were found for each metal among the pulse durations. Conclusion: The results suggested that, regardless of the pulse duration, the current and the spot diameter in relation to the power density (W/cm2) of the laser affected the weld penetration depth into each metal. Cast titanium produced more penetration depth compared to gold alloys because of its low thermal conductivity value and high rate of laser beam absorption. Keywords: adhesion, cast titanium, gold alloys, laser, welding