Owing to a lack of easy access to an individual's electrocardiogram (ECG) data that may be distributed across multiple hospitals, medical practice using serial ECG analysis has not so far been extensively used. Motivated to address this problem, we design and implement an architecture for cross-hospital access to ECG data. The architecture provides a Web portal for retrieving a particular patient's ECG data distributed across a number of ECG data sources. Two important features of this architecture are (1) the distributed search mechanism that uses a master patient index to determine what ECG data sources are likely to contain the ECG data pertaining to a specified patient and (2) the Web service-based interoperable method for accessing disparate ECG data sources. We show that the architecture provides an effective search and retrieval facility for cross-hospital access to ECG data; we show this by implementing and employing a prototype in an experimental scenario consisting of two disparate ECG data sources located at two sites. Our study demonstrates a significant effort to improve the ease of cross-hospital access to ECG data.