Exhibit 21.1 MATRIX SERVICE COMPANY Subsidiaries Matrix Service, Inc., an Oklahoma corporation Matrix Service Mid-Continent, Inc., an Oklahoma corporation San Luis Tank Piping Construction Co., Inc., a Delaware corporation West Coast Industrial Coatings, Inc., a California corporation Matrix Service, Inc. Canada, an Ontario, Canada corporation Midwest Industrial Contractors, Inc., a Delaware corporation Brown Steel Contractors, Inc., a Georgia corporation Georgia Steel Acquisition Corp., an Oklahoma corporation Brown Steel Services, Inc., a Georgia corporation Brown Tanks, Inc., a Georgia corporation Aqua Tanks, Inc., a Georgia corporation San Luis Tank S.A. de C.V., a Mexican corporation Matrix Service, Inc., Panama, a Panama Corporation 53