An implied volatility index reflects the market expectations for the future volatility of the underlying equity index. This study tests and documents the information content, regarding both the realized volatility and the returns of the underlying equity index, of all publicly available implied volatility indices across the world. The empirical findings suggest that implied volatility indices include information about future volatility beyond that contained in past volatility. In addition, we show that there is a statistically significant negative and asymmetric contemporaneous relationship between implied volatility changes and the corresponding underlying equity index returns. Furthermore, this study contributes to the international equity market integration studies by investigating the linkages among major stock exchanges; the basis of the integration analysis is the implied volatility of each market, as proxied by the corresponding implied volatility index and the findings suggest that there is significant integration with respect to market participants' expectations about future uncertainty.