A key problem in providing enterprise-wide information is the integration of databases that have been independently developed. A major requirement is to accommodate heterogeneity and at the same time preserve the autonomy of component databases. This article addresses this problem and presents a strategy to integrate heterogeneous OO schemas. As compared to the existing methodologies, this approach integrates local schemas into a deduction-like global schema. In this way, more semantic relationships of component schemas can be captured, and more complete integration can be obtained. In addition, an efficient algorithm is proposed which can do the integration almost automatically, based on the correspondence assertions supplied by designers. This algorithm is efficient in the sense that the characteristics of assertions are utilized to avoid useless matchings.