In this study, galvanized and austenitic stainless steel sheets were joined to each other by using resistance spot welding. The thicknesses of the galvanized steel and austenitic stainless steel are 0.93 and 1.03 mm, respectively. The experiment parameters are the sheet combination and the weld nugget diameter. Three weld nugget diameters were selected, 4, 5, and 6 mm, which are most widely used in the steel sheet joining industry. Pre-tests were performed to investigate the effect of the welding current on the nugget diameter. By using the pre-test results, series of resistance spot welded steel sheets were obtained with 4, 5 and 6 mm (+/- 0.1) nugget diameters, in the combinations of galvanized - galvanized steel and galvanized - austenitic stainless steel. In the first step of main experiments, spot welded specimens were subjected to tensile tests, and the effect of the sheet combination on the maximal tensile strengths was discussed. In the last step of the investigation, macro photographs of the weld nugget between the steel sheets were taken. The effect of the sheet combination on the nugget formation was discussed and the relationship between the maximal tensile strength and the nugget formation was determined.