Modifications and repairs of removable partial dentures usually involve solder joints. It is important to know the combination of solder and alloy that will provide the strongest junction. The purpose of this work was to investigate the mechanical strengths of different solders commonly used in dental practice. Specimens of three removable partial denture alloys (Dentitan, Crutanium, Wisil) were soldered with various solders having different melting temperatures. The soldered specimens were subjected to tensile testing, and the fracture surfaces were examined by means of scanning electron microscopy. Most of the failures occurred within the soldered joint, which is the weakest portion of a removable partial denture. Excessive use of flux to achieve an adequate flow of solder produced defects in the solder joint. A relationship was found between joint strength and solder fusion temperature for Crutanium and Wisil--the higher the fusion temperature, the higher the joint strength.