Thin films of Co-Ag, Co-Cu, and Fe-Cu alloys were produced by electrochemical deposition. In this study the relationship between the magnetoresistance (MR) ratio and the crystalline state in the electrodeposited alloy films is investigated. Even though for the Co-Ag system it is difficult to form a solid solution, precipitation of phase-separated fine particles or grains is relatively straightforward. It was found that the Co grain (or particle) size becomes smaller with increasing current density (1-10 mA/cm(2)) and the MR ratio also increases. On annealing the film, the MR ratio decreases; For the Co-Cu system, it is easy to produce a solid solution of Co with Cu in the electrodeposited Co-Cu films. The MR ratio for the Co-Cu system increases after annealing.