ASSIGNMENT
                                       AND
                                 FIRST AMENDMENT
                                       TO
                        NET LEASE AND JOINT USE AGREEMENT



                  This  Assignment and First  Amendment (the "First  Amendment")
amends that certain Net Lease and Joint Use Agreement  dated as of March 1, 1994
(the "Lease"), and is entered into by and between L. Randy Knight, a married man
dealing with his sole and separate property ("Landlord"), Knight Transportation,
Inc., an Arizona  corporation  ("Tenant")  and the RK Trust dated as of April 1,
1993, wherein L. Randy Knight is both Trustor and Trustee (the "Trust"),  as the
assignee of the Landlord.

                                    RECITALS
                                    --------

                  The real property subject to the Lease has been transferred by
Landlord to the Trust;

                  Landlord  wishes to transfer and assign the Lease to the Trust
and the Trust  wishes to assume each and every  obligation  of Tenant  under the
Lease and to be substituted as Landlord under the Lease;

                  Tenant is willing to consent to the  transfer  of the Lease to
the Trust and to the  substitution  of the Trust for Randy  Knight,  as Landlord
under the Lease.

                  NOW,  THEREFORE,  for good  and  valuable  consideration,  the
receipt and  sufficiency of which is hereby  acknowledged,  the parties agree as
follows:

                                    AGREEMENT
                                    ---------

                  1. Assignment of Lease.  Landlord hereby transfers and assigns
to the trust all of Landlord's  right,  title and interest in the Lease, and the
Trust hereby accepts such assignment.

                  2. Substitution of Trust as Landlord.  Landlord,  Tenant,  and
the Trust  hereby agree that as of the  effective  date of this  Agreement,  the
Trust  shall  become  the  Landlord  under the Lease and all  references  to the
Landlord  under the Lease shall refer to the Trust.  Tenant  hereby  agrees that
Randy Knight shall have no further  obligations  as Landlord under the Lease and
releases Randy Knight from such obligations.

                  3. Trust  Assumes  Landlord's  Obligations.  The Trust  hereby
assumes and agrees to perform each and every  obligation  of the Landlord  under
the Lease for and on behalf of Randy

                                 Exhibit 10.2.1

Knight.  Knight, as Tenant under the Lease, hereby consents to the assignment of
the Lease to the Trust and the  substitution  of the Trust as Landlord under the
Lease and agrees to render all  performances  required  of the Tenant  under the
Lease to the Trust,  as Landlord,  and hereby  accepts the Trust as the Landlord
under the Lease.

                  4. Terms and Conditions. All other terms and conditions of the
Lease shall remain in full force and effect.  By  execution  of this Lease,  the
parties hereby ratify,  confirm and approve the Lease,  as amended  hereby,  and
agree that the Lease is in full force and effect.

                  5. Effective  Date. This First Amendment shall be effective as
of September 1, 1994.

                  DATED this 19th day of September, 1994.



                                               /s/ Randy Knight
                                        ----------------------------------------
                                        RANDY KNIGHT, former Landlord


                                        KNIGHT TRANSPORTATION, INC.,
                                        an Arizona corporation, Tenant



                                        By          /s/ Kevin P. Knight
                                          --------------------------------------
                                          Its      Chief Executive Officer
                                             -----------------------------------


                                        THE RK TRUST  dated as of April 1, 1993,
                                        wherein L. Randy  Knight is Trustor  and
                                        Trustee  (the  "Trust"),   Assignee  and
                                        substituted Landlord



                                        By          /s/   Randy Knight
                                          --------------------------------------
                                             L. Randy Knight, Trustee
                                       -2-