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The flexural properties of calcium carbonate whisker reinforced cementitious composites (CWRCC) and pure cement mortar at room temperature and after 200 °C, 400 °C, 600 °C and 800 °C elevated temperature exposure were investigated in comparison. The results indicate that the flexural strength and toughness of the specimens showed a trend of increasing first and then decreasing with the increase of calcium carbonate whisker volume fraction at room temperature, and the optimum volume fraction of calcium carbonate whisker was 0. 5%. The effect of the elevated temperatures on the flexural strength and toughness of both CWRCC and pure cement mortar is significant. The flexural strength of each group of specimens showed a linear decrease with the increase of temperature, while the incorporation of calcium carbonate whisker increased the extent of deterioration of the flexural strength by elevated temperature. The flexural toughness of each group of specimens showed a trend of increasing first and then decreasing with the increase of temperature. The incorporation of calcium carbonate whisker increased the onset temperature of the decrease of the flexural toughness at elevated tempera¬ture, while t reduced the increase and increased the decrease of the flexural toughness at elevated temperature simultaneously. Compared to pure cement mortar, the incorporation of calcium carbonate whisker improved the flexural strength and toughness of specimens at the same temperature from 20 °C to 600 °C, while the flexural strength and toughness of CWRCC did not differ much from those of pure cement mortar after exposed to 800 °C. [ABSTRACT FROM AUTHOR]