• Martinsen Mayer Ltd.

• Mason Alexander

• Masterlink Logistics

• Matrix Recruitment Group

• Matrix Resources

• Matthew Jeffers Test Company

• Maven TM

• MBN International Systems Ltd.

• McCann FitzGerald

• McLernons Computers

• Mcor technologies

• MediaTeam

• Mediolanum

• MedMedia Group

• Medserv

• Meghen Group

• Meritec

• Methodius IT Recruitment

• MG International

• MI5

• Microexchanges

• Microsoft Ireland

• Microsoft Ireland Research

• Midas Technologies