The aim of the study was to determine if the increase in radiopacity provided by bismuth oxide is related to the color alteration of calcium silicate-based cement. Calcium silicate cement (CSC) was mixed with 0%, 15%, 20%, 30% and 50% of bismuth oxide (BO), determined by weight. Mineral trioxide aggregate (MTA) was the control group. The radiopacity test was performed according to ISO 6876/2001. The color was evaluated using the CIE system. The assessments were performed after 24 hours, 7 and 30 days of setting time, using a spectrophotometer to obtain the δE, δa, δb and δL values. The statistical analyses were performed using the Kruskal-Wallis/Dunn and ANOVA/ Tukey tests (p < 0.05). The cements in which bismuth oxide was added showed radiopacity corresponding to the ISO recommendations ( > 3 mm equivalent of Al). The MTA group was statistically similar to the CSC/30% BO group (p > 0.05). In regard to color, the increase of bismuth oxide resulted in a decrease in the δE value of the calcium silicate cement. The CSC group presented statistically higher δE values than the CSC/50% BO group (p < 0.05). The comparison between 24 hours and 7 days showed higher δE for the MTA group, with statistical differences for the CSC/15% BO and CSC/50% BO groups (p < 0.05). After 30 days, CSC showed statistically higher δE values than CSC/30% BO and CSC/50% BO (p < 0.05). In conclusion, the increase in radiopacity provided by bismuth oxide has no relation to the color alteration of calcium silicate-based cements.