The aim of this study was to investigate the mechanical properties and microstructure of cobalt-chromium alloy cast circumferential clasps recycled in 50:50 mixing ratios by weight of used alloy and new alloy. Thirty circumferential clasp samples made from cobalt-chromium alloy were divided into 3 groups (n = 10 per group) : 100% new alloy, 50% used alloy mixed with 50% new alloy, and 100% used alloy; the used alloy was melted only once. Ten samples per group were tested on the universal testing machine with a crosshead speed of 0.5 mm/min. The load to fracture and load to permanent deformation were recorded. One-way analysis of variance and LSD multiple comparison tests were used to compare the results of the 3 groups (a= 0.05). Three selected samples from each group were examined the fractured surface using a Scanning Electron Microscope (SEM) and analyzed elements with Energy dispersive spectroscopy (EDS). The results showed that the mean load to fracture of the three groups were not significantly different (p < .05). The mean load to permanent deformation of the 100% new alloy cast clasps was not significantly different from that of the 50% used alloy mixed with 50% new alloy cast clasps but was significantly greater than that of the 100% used alloy cast clasps (p < .05). SEM examination revealed that contamination increased with the ratio of used alloy. In conclusion, the use of used cobalt-chromium alloy reduces the mechanical property of the cast clasp which may result from contamination of the inclusions in the alloy.