This volume constitutes the proceedings of the 4th International Conference on E-Technologies, MCETECH 2009, held in Ottawa, Canada, during May 4-6, 2009.

The 23 full and 4 short papers included in this volume were carefully reviewed and selected from a total of 42 submissions. They cover topics such as inter-organzational processes, service-oriented architectures, security and trust, middleware infrastructures, open source and open environments, and applications including eGovernment, eEducation, and eHealth.