For immediate release: July 16, 2004

MDA's Second Quarter Earnings Conference Call Alert

Richmond, B.C. - MacDonald, Dettwiler and Associates Ltd. (TSX: MDA), a provider of essential information solutions, plans to release second quarter 2004 financial results at close of market on Thursday, July 22nd.

MDA will host an earnings conference call, featuring remarks by President and CEO Daniel Friedmann, and Anil Wirasekara, Executive Vice-President and CFO, followed by a Q & A session.

The call is scheduled to begin promptly at 4:30pm Eastern Time, (1:30pm Pacific Time).

To participate, please call the conference line approximately five minutes prior to the commencement of the call:

Toll free in North America: 1-800-387-6216

In Toronto: 416-405-9328

The conference call will also be Webcast live and then archived at:

http://www.mda.ca/investor/events.shtml

Related Websites:
www.mdacorporation.com


For more information, please contact:

Wendy Keyzer
External Relations
MDA
Telephone: 604-231-2743
E-mail: wendy@mdacorporation.com