Antitrust Improvements Act of 1999 - Amends the Clayton Act to prohibit a large local telephone company, including any affiliate thereof, from merging with or acquiring a controlling interest in another large local telephone company unless: (1) the Attorney General finds that the proposed merger or acquisition will promote competition for telephone exchange services and exchange access services; and (2) the Federal Communications Commission (FCC) finds that each large local telephone company that is a party to the proposed merger or acquisition, with respect to at least half of the access lines in each State served by that company, of which at least half are residential access lines, has fully implemented requirements of the Communications Act of 1934 regarding interconnection and procedures for negotiation, arbitration, and approval of agreements.

Requires: (1) the Attorney General, not later than ten days after making a finding that the proposed merger or acquisition will promote competition, to submit to the House and Senate Judiciary Committees a report on the finding, including an analysis of the effect of the merger or acquisition on competition in the U.S. telecommunications industry; (2) each large local telephone company or affiliate proposing to merge with or acquire a controlling interest in another large local telephone company to file an application with respect to the merger or acquisition with the Attorney General and the FCC on the same day; and (3) the Attorney General and the FCC to issue a decision regarding the application within the time period applicable to review of mergers under the Clayton Act.

Vests the U.S. district courts with jurisdiction to prevent and restrain any mergers or acquisitions that are inconsistent with one of the findings under this Act.

Authorizes the Attorney General to institute proceedings in any U.S. district court in the district in which the defendant resides, is found, or has an agent. Requires that court to order such injunctive and other relief as appropriate if: (1) the Attorney General makes a finding that a proposed merger or acquisition covered by the application does not meet the condition specified; or (2) the FCC makes a finding that one or more of the parties to the proposed merger or acquisition do not meet the requirements specified in this Act.