An Holter open system was developed for collection, retrieval and management of data produced by commercial monitoring devices. It is based on four modules interconnected to form an integrated system: ECG analysis equipment, relational database, Java application for direct access to the DBMS, Web-script library for safe access to patient information (data consultation, extraction of summaries of lab activity and computing both administrative and clinical statistical indices). Relevant data can be exported in XML format to facilitate data migration to other hospitals or to qualified external physicians. The software driver can be easily changed according to data format of input devices. Use of Java language and Web scripts allows the setup of client workstation according to user preferences or lab configuration (PC, Mac or Unix). The system might be configured as "standalone" or as "integrated" with external Hospital Information System for data exchange.