Customs could be losing millions of dollars in duties and other collections due to fraud and abuse because of an almost total breakdown of internal controls over its pre-numbered collection documents. Although the total is unknown, Customs estimates that several million collection documents could not be accounted for following nationwide inventories conducted in fiscal years 1987 and 1988. The lack of internal controls over pre-numbered collection documents and the staggering number of unaccounted for documents provide an enormous potential for abuse and cover-up. Recommendations include (1) discontinuation of the use of the current pre-numbered collection documents; (2) enforcement of stringent internal controls over the assignment and use of the new pre-numbered documents; and (3) reporting the lack of internal controls over pre-numbered collection documents as a material weakness under the Federal Managers' Financial Integrity Act and reporting the status of corrective actions taken. 1 table, 2 figures, appendix.