<Page> Exhibit 99.906CERT CERTIFICATIONS PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002 David G. Booth, Principal Executive Officer, and Michael T. Scardina, Principal Accounting Officer, of The DFA Investment Trust Company, a Delaware statutory trust (the "Registrant"), each certify that: 1. The Registrant's periodic report on Form N-CSR for the period ended November 30, 2003 (the "Form N-CSR") fully complies with the requirements of Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934, as amended, as applicable; and 2. The information contained in the Form N-CSR fairly presents, in all material respects, the financial condition and results of operations of the Registrant. By: /s/David G. Booth ------------------------ David G. Booth Principal Executive Officer The DFA Investment Trust Company Date: 2/3/04 ------------- By: /s/ Michael T. Scardina ------------------------ Michael T. Scardina Principal Accounting Officer The DFA Investment Trust Company Date: 2/3/04 -------------