Exhibit 99.1


                            CERTIFICATION PURSUANT TO
                             18 U.S.C. SECTION 1350,
                             AS ADOPTED PURSUANT TO
                  SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection  with the Quarterly  Report of Arch Coal,  Inc. (the "Company") on
Form 10-Q for the period ending  September 30, 2002 as filed with the Securities
and Exchange  Commission  on the date hereof (the  "Report"),  the  undersigned,
Steven F. Leer, Chief Executive Officer of the Company,  certify, pursuant to 18
U.S.C.  ss. 1350, as adopted  pursuant to ss. 906 of the  Sarbanes-Oxley  Act of
2002, that:

          (1) The Report fully complies with the requirements of section 13(a)
or 15(d) of the Securities Exchange Act of 1934; and

          (2) The information contained in the Report fairly presents, in all
material respects, the financial condition and results of operations of the
Company.

                                                     /s/ Steven F. Leer
                                              --------------------------------
                                                     Steven F. Leer
                                                     Chief Executive Officer
                                                     November 12, 2002