(Reported to House from the Committee on Agriculture with amendment, H. Rept. 99-736 (Part I)) Agricultural Export Act of 1986 - Amends the Food Security Act of 1985, effective for the period ending September 30, 1988, to provide that under the export enhancement program the Secretary of Agriculture shall permit program participation by foreign purchasers who: (1) traditionally have purchased U.S. agricultural commodities and products; (2) maintain U.S. trade relations; and (3) after July 30, 1986, comply with minimum purchase requirements under long-term grain agreements. Directs the Secretary to give priority to foreign purchasers who have traditionally purchased such commodities and continue to purchase at historic levels, or who begin to purchase in quantities greater than previous purchase levels. Directs the Secretary, to the maximum extent practicable, to use commodities with a cumulative value of not less than $667,000,000 to carry out such program through FY 1987. Directs the Secretary to report to the Congress by March 31, 1987, with a list of nonparticipating traditional purchasers and explanations for such nonparticipation. Authorizes the Secretary to make exceptions to the program prohibitions against resale, transshipment, or nondomestic use.